By Tal Kopan CNN

WASHINGTON (CNN) -- The FBI is investigating any possible coordination between members of the Trump presidential campaign and Russia, and there is no evidence of wiretaps on Trump Tower.

Those were some of the takeaways from a lengthy hearing Monday where the directors of the FBI and National Security Agency testified before the House Intelligence Committee covering Russian interference in the 2016 election.

FBI Director James Comey and National Security Agency Director Mike Rogers spent hours answering questions from members of Congress on both sides of the aisle.

Here are some of the key things we learned.

There is an investigation and it started in July

In his opening statement, Comey publicly confirmed for the first time that the FBI does have an open investigation into allegations that there was coordination between Russia and President Donald Trump's campaign as part of a broader investigation into Russia's interference in the 2016 election.

"As with any counterintelligence investigation, this will also include an assessment of whether any crimes were committed," Comey's statement added.

He told lawmakers that the investigation began in "late July," but because it is ongoing there were many details he could not comment on.

There was no wiretapping

It did not take long for the hearing to pour cold water on Trump's repeated claims, through tweets, that former President Barack Obama somehow ordered wiretapping and surveillance of Trump Tower.

"I have no information that supports those tweets," Comey said, adding that the Justice Department authorized him to speak for them as well as the FBI in the matter.

Comey also said that it would be impossible for any president to order a wiretapping operation against anyone.

The Obama-ordered assessment -- referenced by Clapper -- did not deal with collusion

The ranking member of the committee, Rep. Adam Schiff, sought to clarify with Comey that his corroboration of former Director of National Intelligence James Clapper's statements about not finding evidence of Trump-Russia coordination referred to an intelligence community report that didn't assess the topic.

"Yes. I understood the question to be about the report itself," Comey said.

"The unclassified intelligence assessment doesn't discuss the issue of US person coordination with the Russians," Schiff said. "And I assume that's because, at the time of the report in January of this year, that was under an investigation that you have now disclosed, is that right? "

"Correct," Comey said. "The counterintelligence investigation is the FBI's business."

The Democrats are still hammering coordination

While no evidence of coordination between the Trump campaign and the Russians was confirmed or proffered Monday, Democrats repeatedly returned to the topic, asking Comey and Rogers several series of questions they for the most part could not comment on.

Many of the Democrats used the hearing as an opportunity to get concerns on the record or, they said, to make sure Comey was aware of them, including meetings or contacts between Trump-linked officials and Russian contacts.

"Is it possible that all of these events and reports are completely unrelated and nothing more than an entirely unhappy coincidence? Yes, it is possible," said Schiff in his opening remarks. "But it is also possible, maybe more than possible, that they are not coincidental, not disconnected and not unrelated, and that the Russians used the same techniques to corrupt US persons that they have employed in Europe and elsewhere. We simply don't know, not yet, and we owe it to the country to find out."

We still don't know if there was coordination

No evidence was presented, but Comey said the investigation was only in its beginning stages.

Comey said due to the ongoing nature of the investigation, there were many things he could not comment on -- and he added his "no comment" responses shouldn't be interpreted, either.

"Because it is an open ongoing investigation and is classified, I cannot say more about what we are doing and whose conduct we are examining," Comey said. "I know that is extremely frustrating to some folks. I hope you and the American people can understand."

Some agencies can 'unmask'

The notion of "unmasking" Americans came up several times, prompted by Republican lawmakers' anger over the leaks that former national security adviser Mike Flynn was caught up in the US surveillance net during his conversations with Russian officials.

Normally, US persons caught up in surveillance of foreigners would be masked, or their names kept confidential, so lawmakers asked Rogers and Comey who would have authority to reveal a person's identity.

Rogers said there were 20 people at NSA, including himself, who could do so.

"If it's criminal activity (caught during surveillance), we'll disseminate the information, and if the FBI or other criminal activities are on the reporting stream, in some cases I also will generate a signed letter under my signature in specific cases to Department of Justice highlighting that what we think we have is potential criminal activity," Rogers said. "But because we are not a law enforcement or justice organization we're not in a place to make that determination."

Rogers and Comey confirmed that other agency directors, such as those at Justice and the CIA, would also be able to request a person's name be unmasked. But Comey said the White House could only make such a request to the agency that collected the information.

Comey references the Clinton elephant in the room

Comey wasn't asked about it directly, but in his opening statement he obliquely referenced a chief complaint of Democrats -- that he spoke freely about an investigation into Hillary Clinton but not Trump's campaign during the election.

He said that talking about closed investigations was different.

"Some folks may want to make comparisons to past instances where the Department of Justice and the FBI have spoken about the details of some investigations, but please keep in mind that those involved the details of completed investigations," Comey said. "Our ability to share details with the Congress and the American people is limited when those investigations are still open, which I hope makes sense."

The DNC was warned

The FBI warned the Democratic National Committee long before they were publicly victims of a massive hack that divulged embarrassing emails on the eve of the party's convention.

Comey said his agency first notified the DNC in August 2015, nearly a full year before the party discovered the intrusion into its system and hired outside help to kick the Russian hackers out.

The FBI director also confirmed reports that after the hack the DNC did not give the FBI access to its computer systems or networks for forensic investigation to support the FBI's conclusion that Russian hackers were responsible.

But Comey did say he wished the bureau could have been more aggressive in warning the DNC in hindsight.

No votes were changed

Rogers and Comey both testified that despite the intense Russian hacking and propaganda effort aimed at public opinion, no actual votes in the election were compromised.

House Intelligence Chairman Devin Nunes listed several key swing states -- Michigan, Wisconsin, Pennsylvania, Florida, North Carolina and Ohio -- and asked Rogers if there was any evidence that vote tallies were changed.

But the directors would not go so far as to say the election was not influenced by the overall Russian campaign.

Responding to a tweet from the White House that included a video of the hearing and asserted that Comey and Rogers testified that Russia had not influenced the process, both said that was not their intention.

"It was not our intention to say that today," Comey said, adding it's not "something that we looked at" as part of intelligence community review of the election.

CNN's Stephen Collinson, Adam Levine, Tom LoBianco, Mike Callahan, Manu Raju and Donald Judd contributed to this report.

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