By Ray Sanchez and Emily Smith, CNN

(CNN) -- A number of similar crude explosive devices have been sent since Monday to former President Barack Obama, Hillary Clinton, other top political figures and CNN's New York offices.

Here is a timeline:

Thursday

Authorities responded early Thursday morning to a suspicious package that had been sent to actor-director Robert De Niro at a building in Lower Manhattan's Tribeca neighborhood. The address, 375 Greenwich St., matches that of the Tribeca Film Center.

The package had actually been received in the general mail room on Wednesday, according to a law enforcement official. A retired police officer discovered it and left it in his office. After seeing news reports he realized it was similar to other packages in the news and called police at about 4 a.m. on Thursday, according to the official.

The package was removed from the building around 7 a.m.

Authorities also located two suspicious packages addressed to former Vice President Joe Biden at post offices in Delaware, a law enforcement official said. The packages were similar to others discovered this week and contained potential explosive devices. At least one of them was misaddressed and returned to sender, two law enforcement sources told CNN.

Wednesday

A suspicious package was sent to the Florida office of Democratic Rep. Debbie Wasserman Schultz on Wednesday morning. It was intended for former US Attorney General Eric Holder but had the wrong address. The package was returned to the Democratic congresswoman because her office was the return label on the package, two law enforcement sources said.

CNN's New York bureau in the Time Warner Center was evacuated shortly after 10 a.m. Wednesday after the discovery of a package containing a bomb, said law enforcement officials. They said the package was addressed to former CIA Director John Brennan, who has appeared on CNN.

A suspicious package addressed to the Washington office of US Rep. Maxine Waters, D-California, was intercepted at a congressional mail-screening facility in Maryland, and a second package addressed to the congresswoman was found at a postal facility in Los Angeles. It matches the description of those sent to the other officials.

A package containing a possible explosive device intended for Obama was intercepted by the US Secret Service at a screening facility in Washington.

Tuesday

A package containing a possible explosive device and intended for Clinton, the former secretary of state and first lady, was intercepted. It was discovered during routine mail screening procedures Tuesday evening, according to authorities.

Monday

A suspicious package targeting billionaire investor and philanthropist George Soros was rendered safe in Bedford, New York, a law enforcement source told CNN. Bedford police said they received a call about 3:45 p.m. Monday reporting a suspicious package found in a mailbox. The package appeared to be an explosive device, police said.

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