Montgomery County police on Wednesday released dramatic surveillance video as they appealed to the public’s help as they investigate an armed robbery at a 7-Eleven earlier this month in Laytonsville.

Just before midnight on April 9, officers were called to the store at 6850 Laytonsville Road. They learned that three masked suspects, all armed with handguns, rushed into the store.

Two leapt over the counter and assaulted the clerk, police said. The third ordered customers and employees to the ground.

At least one of the suspects grabbed cash from a register, and the three fled. A clerk was hurt, and was treated and released from a local hospital, according to police.

Anyone with information is asked to call 240-773-5100. Those who want to remain anonymous or be eligible for a reward of up to $1,000 can call 1-866-411-TIPS (8477) or 240-773-TIPS (8477). Anonymous tips also can be provided by typing “MCPD” plus the tip on a cell phone or PDA and texting it to 274637 (CRIMES), police said.