A clerk at a Methuen convenience store fought off a man who tried to rob the store at knifepoint, and Methuen police have posted a video in hopes of capturing the suspect.

Police wrote on their Facebook account that the thief entered the Stop Quick Convenience Store on Haverhill Street around 4:12 p.m. Wednesday, demanding cash.

The clerk fought back, hitting the thief with a thin rod and also locking the door so the suspect could not leave, police said. The video shows the clerk continually striking the thief, who grabs the cash register, uses it to smash the glass door, and then crawls out of the door frame to the parking lot. Police recovered a knife at the scene.

The suspect was described as a white man, about 6 feet 4 inches tall, about 35 years old.

Police asked anyone with information to contact them at 978-983-8698 or reach out to Methuen Police Detective Rick Pilz at 978-983-8783.

John Ellement can be reached at ellement@globe.com.