Developments in the Boston Marathon bombings investigation have come quickly since the release of photos of the suspects.
5 p.m. ET: The FBI releases pictures of two male suspects being sought in connection with the Boston Marathon bombings.
Late Thursday: A robbery is reported at a convenience store. Massachusetts State Police spokesman Col. Timothy Alben initially said the two bombing suspects robbed the store. He later backtracked, saying the two men didn't rob a store, but one of the suspects was seen on security video from the store.
11 p.m.: Police respond to a call on the campus of the Massachusetts Institute of Technology, where university police officer Sean Collier, 26, was shot. He died from his injuries. Police believe the bombing suspects were responsible for the shooting.
Early hours: Police say the two suspects hijack a car at gunpoint in Cambridge, Massachusetts, taking the driver as a hostage. The suspects tell the driver they are the Boston marathon bombers, a law enforcement source told CNN's Joe Johns.
Early hours: The hostage is released at a gas station.
Early hours: At one point, the suspects pull over to transfer materials into their new car, two federal officials said.
1 a.m.: Police, who were tracking the vehicle using its built-in GPS system, pick up the chase in Watertown. The pursuit goes into a residential neighborhood, with the suspects throwing explosives and firing shots at officers, police said.
The suspects threw one grenade and five pipe bombs at police chasing them, one FBI and one Department of Homeland Security official told CNN. Three of those explosives detonated, two did not, the officials said.
Officers fire back, with Gov. Deval Patrick later estimating that 200 rounds of gunfire were exchanged in the firefight.
One suspect is injured. He is later identified as Tamerlan Tsarnaev, and pronounced dead at a hospital. A source briefed on the investigation says Tamerlan Tsarnaev was wearing explosives and an explosive trigger at the time. After he is shot, his brother drives away, according to the source.
Transit officer Richard H. Donohue Jr., a 33-year veteran of the force, is shot and wounded in the Watertown exchange. Fifteen police officers are treated at St. Elizabeth's Medical Center in nearby Brighton for injuries suffered in the episode, according to hospital spokeswoman Jennifer Kovalich.
Authorities later announce that they recovered a pressure-cooker bomb after the pursuit into Watertown, a source briefed on the ongoing investigation said. They also recovered a significant amount of homemade explosives in Watertown, Massachusetts State Police spokesman David Procopio said.
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 that they will be closed for the day because of police activity.
8 a.m.: Sources identify the dead suspect as Tamerlan Tsarnaev, 26, and the suspect on the run as his brother, Dzhokar Tsarnaev, 19.
8 a.m.: Boston-area residents are asked by authorities to stay inside as the hunt continues for Dzhokar 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.
All day: Hundreds of law enforcement officers go door-to-door on 20 streets in Watertown, looking for Dzhokar Tsarnaev. Alben, the state police spokesman, says the suspect fled on foot and that authorities still believe he's in Massachusetts.
11:30 a.m.: The uncle of the Tsarnaev brothers tells reporters that he is "ashamed" to be related to the suspects. He calls those responsible for the bombings "losers." Speaking outside his Montgomery County, Maryland, home, Ruslan Tsarni says that his nephew Dzhokar Tsarnaev "has put a shame on our family, a shame on the entire ethnicity" and should turn himself in.
12:20 p.m.: The University of Massachusetts-Dartmouth is evacuated, and the school says that Dzhokar Tsarnaev was an enrolled student. Law enforcement personnel swarm the campus, which is just west of New Bedford and about 60 miles south of Boston.
3:15 p.m.: Numerous activities scheduled for Friday night are canceled around Boston -- including Boston Red Sox and Boston Bruins games, as well as a Big Apple Circus show -- because of the ongoing manhunt for the marathon bombing suspect.
6 p.m. The lockdown for the Boston area is lifted, meaning people can again leave their homes, even though a suspect remains at large. The area's public transit system, known as the T, also returns to service after being shut down most of the day, the governor said.