Residents in Central Square on Monday night saw a police foot chase into traffic that brought down two men suspected in a deal for drugs, a gun or both.

At about 9:30 p.m. Monday, a Cambridge Police Detective in plainclothes saw a man he suspected was carrying a gun and followed him, police spokesman Dan Riviello said. That’s when the officer saw what he believed was a transaction taking place and identified himself to one of the suspects as a police officer.

The man fled on foot through Central Square, running into traffic before being taken to the ground and subdued by the detective and other responding officers, Riviello said. The suspect had a backpack holding a gun for which he could not produce a license or firearms identification card.

A second suspect was spotted and pursued through Central Square by police before being arrested.

A bag with 20 grams of marijuana was found on the suspects, police said.

One of the suspects is a Cambridge resident: Daqwan Collins, 17, of 55 Columbia St., faces charges of possession of a large-capacity firearm, disorderly conduct, conspiracy to violate drug law, defacing a firearm serial number, carrying a firearm without license and possession of a firearm or ammunition without an FID card.

Rameses Canelus, 26, of 35 Hammond St., Roxbury, faces those charges as well as well as two more: possession to distribute a Class D drug and a drug violation near a school or park.

“Our streets are now safer due to the excellent work of an observant Cambridge Police Detective and his colleagues,” Cambridge Police Commissioner Robert C. Haas said. “Running into traffic and risking injury, our officers and detectives are a true example of bravery and dedication.”

This post was written from a press release.