A third teenager has been charged with assaulting a federal officer during an attempt to carjack a scooter.

D.C. police arrested 19-year-old Thomas Cooley, of Northwest, on Wednesday. Cooley was charged with carjacking and assault on a police officer.

A 17-year-old boy and a 15-year-old boy were arrested Tuesday and they face the same charges, police said.

David Lesansky was riding his motor scooter near the intersection of Pennsylvania Avenue and Potomac Avenue SE about noon Friday when the three suspects approached. Lesansky was off-duty.

"I came to a stop at the stop light," Lesansky told News4 while recovering on his couch.

Then, the brutal assault began.

"They punched me multiple times. Likely kicked me," Lesansky said.

The perpetrators continued the beating even after Lesansky identified himself as an officer, police say.

But Lesansky didn't give up his scooter easily.

"They pushed me over. I fell down. The scooter went down," he said. "I took my helmet off and began struggling with them."

Eventually, the assailants gave up. They were caught on surveillance camera as they ran away. The third suspect has not been captured.

Lesansky's scooter wasn't stolen, but he was left with bruises and internal injuries to his ribs, abdomen and back.

"The pain is very intense," he said.

Police say the assault remains under investigation.

Anyone with information that can help police should call 202-727-9099.