Here are the key developments related to the search for the Boston Marathon bombing suspects, based on reports from Massachusetts State Police and Boston police.

Thursday 5 p.m.

The FBI releases images of two men they say they would like to question in connection with the marathon bombings. The images depict two young men, each wearing a baseball cap near the finish line. FBI identifies the two men as Suspect 1 and Suspect 2

The FBI says Suspect 2, pictured in a white hat, was seen setting down a bag at the site of the second of two deadly explosions.

10 p.m.

Police are alerted that two men are trying to rob a 7-Eleven convenience store near the MIT (Massachusetts Institute of Technology) campus in Cambridge. Suspect 2 is identified in the security camera footage as one of the suspected robbers. He’s seen wearing a grey hoodie.

10:30 p.m.

A university police officer responds to a report of a disturbance. He is later found inside his cruiser with multiple gunshot wounds. The officer is taken to Massachusetts General Hospital, where he is pronounced dead.

Around the same time, police receive reports of an armed carjacking of a Mercedes SUV by two males. The carjacking victim is reportedly kept in the car with the suspects for approximately a half hour. The victim is later released uninjured, at a Cambridge gas station. Police immediately begin to search for the vehicle and pursue it into Watertown.

11 p.m.

As the police are chasing the vehicle, Cambridge Police say explosive devices were thrown from car by the suspects. The suspects and officers in a police SUV exchange gunfire.

As police try to stop the vehicle, the suspects throw out a large, unwieldy bomb that witnesses say looks like a pressure cooker. It explodes.

One of the suspects, Suspect 1, possibly with an improvised explosive device strapped to his body, runs toward the officers. He is tackled. It’s not clear if he is also shot.

Meanwhile, Suspect 2 gets back into the SUV and tries to drive into the officers. The officers scatter and the SUV drives away.

During the exchange, an officer with the (Massachusetts Bay Transportation Authority) is seriously injured and taken to hospital.

Friday, 1 a.m.

Authorities pursue the other escaped suspect to a neighbourhood in Watertown. A manhunt begins on foot, as a helicopter circles overhead. Residents are told to keep their doors locked.

1:30 a.m.

Suspect 1, who charged at the officers, is taken to hospital with critical injuries, where he is pronounced dead at 1:35 a.m.

2 a.m.

The FBI releases new photos of the suspects, with clearer images of their faces and one photo of the men together. The images were apparently taken from security camera footage from the 7-Eleven convenience store robbery.

5:30 a.m.

With thousands of officers involved in the search, all vehicle traffic is suspended in and out of Watertown. Residents in nearby Newton, Arlington, Waltham, Belmont, Cambridge and the Allston-Brighton neighbourhoods of Boston are ordered to stay indoors.

6 a.m.

Massachusetts Governor Deval Patrick suspends service on all public transit services in the MBTA in Boston. As well, all local businesses are asked not to open and all taxi services stop running. Hospitals in the city have also entered lockdown mode and no patients are being discharged.

9 a.m.

Gov. Patrick asks all residents in the entire city of Boston to “shelter in place” -- stay inside and refuse to open their doors to anyone except police with proper identification.