Police have arrested a 42-year-old man on charges he tried to blow up a Boston Police cruiser Friday morning.

Boston Police Commissioner William Evans announced Sunday that police arrested Asim Kieta on arson, assault with intent to murder and other charges Saturday night in Charlestown.

Police said Kieta is homeless but is from the Dorchester area.

Investigators are now working on a possible motive.

"We're not clear on the motive," Evans said. "He has a lengthy criminal past. He's been in and out of jail.

The commissioner said police are trying to determine "whether there is a hatred for police because of his past behavior or whether this is some nexus to what is going on in the world as far as terrorism."

An officer was driving by the Boston Police substation on West Broadway in South Boston and saw a fire near a police cruiser Friday around 8:15 a.m., police said.

Police moved the cruiser and a device exploded. The device appeared to be a propane tank, but authorities are still working to determine the specific type of device used, Evans said.

There was some type of firework or explosive device on the tank, the commissioner said. There were two explosions. Evans said there were minor injuries, but no serious injuries.

Evans said investigators worked with the FBI and Daniel Bennett, the state Secretary of the Executive Office of Public Safety and Security, in order to find Kieta.

Through surveillance images and witness accounts, police were able to place a car at the scene. Police said Kieta was seen leaving the car with a grocery bag and then heading back to the car.

Investigators then began searching for the vehicle. They found Kieta in his car in Charlestown.

"I'm glad we got this dangerous guy off the streets," Evans said.

Police said the booking photograph of Kieta was not released because of the ongoing investigation.

Kieta was charge with possession of an explosive device, assault with intent to murder, assault and battery with a dangerous weapon, assault and battery on a police officer and arson of personal property."