Developments in the Boston Marathon bombings investigation have come quickly since the release of the photos of the suspects:
|Officer Sean Collier|
5 p.m. -- The FBI releases pictures of two male suspects they are seeking in connection with the Boston Marathon bombings.
Late Thursday -- A robbery is reported at a 7/11 convenience store, not long after the FBI released images of the suspects.
11 p.m. -- Police respond to a call on the campus of the Massachusetts Institute of Technology, where university police officer Sean Collier was shot. He died from his injuries.
Boston bombing suspect Dzhokar Tsarnaev has a Twitter account and has tweeted since the bombing, friends of his told CNN. His tweets included one early Wednesday at 1:43 a.m. that said, "I'm a stress free kind of guy." On April 15 at 8:04 p.m. -- hours after the bombings -- he tweeted a quote from rapper Jay-Z, "Ain't no love in the heart of the city, stay safe people."
Early hours -- The two suspects allegedly hijacked a car at gunpoint in Cambridge, Massachusetts, taking the driver as a hostage.
Early hours -- The hostage is released at a gas station.
Early hours --As officers began to chase, the suspects threw explosives and fired shots at the officers. Officers fired back, striking a man, who was pronounced dead at the hospital.
Early hours -- Another policeman, transit officer Richard H. Donohue Jr., was shot and wounded.
1 a.m. -- Dozens of police rush into the Watertown, Massachusetts, area.
2 a.m. -- Police begin ordering residents in Watertown to turn off their cell phones
7 a.m. -- At least 12 universities and colleges, along with Boston Public Schools and Cambridge Public Schools announce they will be closed for the day due to police activity.
8 a.m. -- Sources identify the dead suspect as Tamerlan Tsarnaev, 26, and the suspect on the run as his brother Dzhokhar Tsarnaev, 19.
8 a.m. -- Boston-area residents are asked by authorities to stay inside as the manhunt continues for Dzhokhar Tsarnaev.
9 a.m. -- The slain suspect, Tamerlan Tsarnaev, was wearing explosives and an explosive trigger when his body was recovered, a source briefed on the investigation tells CNN.