A fast-moving robbery suspect who hit a series of banks in Montgomery and Prince George’s counties on Thursday was arrested two hours after his crime spree, authorities said.

In one 15-minute stretch, the suspect allegedly robbed three banks in Montgomery — starting in Chevy Chase and working north through Kensington and into the Wheaton area, police said. He also robbed at least one bank in Prince George’s County.

Officials did not immediately release the suspect’s name, and planned to provide more details at a news conference on Friday. The suspect’s exact motive, and why he wanted to rob banks so quickly, wasn’t clear.

The suspect was arrested in the Glenarden area of Prince George’s, after a robbery sergeant leaving a restaurant spotted a Toyota Corolla matching a description of the car the suspect had used.

The Montgomery heists, along a 3.5-mile stretch, started just before lunchtime. That they would proceed over such a short duration was surprising.

“This would be unusual in any jurisdiction,” said Officer Rick Goodale, a Montgomery police spokesman.

Detectives continue to investigate if the suspect had a gun, or he just implied that he was armed, Goodale said. Detectives also are trying to determine if the suspect had help.

Goodale listed the three Montgomery robberies as occurring at:

● 11:20 a.m., SunTrust Bank, 8510 Connecticut Ave., Chevy Chase

● 11:29 a.m., Capital One Bank, 10707 Connecticut Ave., Kensington

● 11:35 a.m., BB&T Bank, 2909 University Blvd. West, near downtown Wheaton.

Police in Prince George’s on Thursday night confirmed the suspect was connected to at least one bank robbery in the county, adding that the case was still being investigated.