5:10 p.m. FBI releases photos and videos of suspects in the Boston Marathon bombings.
Sometime around 10 p.m. A video camera in a Cambridge convenience store captures one of the suspects. Contrary to earlier reports, Cambridge police say no robbery occurred.
10:20 p.m. Reports of shots fired on the MIT campus.
10:30 p.m. MIT police officer Sean Collier, 26, of Somerville, Mass., is found shot in his cruiser at Main and Vassar streets. He is rushed to Massachusetts General Hospital, where he is pronounced dead.
11:30 p.m. Suspects carjack a Mercedes SUV at gunpoint.
12 a.m. The cars owner escapes at a gas station on Memorial Drive. SUV heads toward Watertown. Police give chase. Suspects throw explosive devices at police from the car.
12:45-1 a.m. Gunfire breaks out between suspects and police near Dexter and Laurel streets in Watertown. Transit Authority Police Officer Richard H. Donohue is shot and wounded. He is taken to Mt. Auburn Hospital for treatment.
About 1 a.m. Suspect #1, later identified as Tamerlan Tsarnaev, 26, is brought to Beth Israel Deaconess Medical Center with multiple traumatic wounds. Massive manhunt begins for Suspect #2.
1:35 a.m. Suspect #1 pronounced dead.
2 a.m. FBI releases new photos of Suspect #2, later identified as Dzhokhar A. Tsarnaev, 19.
4:30 a.m. Police confirm Suspects #1 and #2 are Boston Marathon bombing suspects, advise Watertown area residents to stay in their homes.
5:30 a.m. Massachusetts Gov. Deval Patrick suspends all public transit service.
8 a.m. Patrick urges all Boston residents to stay indoors.
8:30 a.m. FAA closes airspace over Watertown.
Compiled by Lindsay Wise
Emma Kantrowitz and Anne-Kathrin Gerstlauer of the Washington Bureau contributed.