Police are looking for a heavyset guy, over 200 pounds, who held up a Branch Street convenience store with a rifle or a long-barrelled BB gun tonight, police said.

Officers went to Country Farms, at 268 Branch St., at 9:37 p.m., but soon learned the robbery had about 5 minutes on it.

The suspect pulled what appeared to be a rifle and fled across Middlesex Street toward Wilder Street and Columbus Avenue.

He's described as a heavyset, white male, over 200 pounds, wearing a dark blue or black jacket with gray lining, a dark sweatshirt with writing across the front, gray sweatpants with a band around the ankles, and a baseball cap with an insignia on it.

Anyone with information is asked to call Lowell police at (978) 937-3200 or Crimestoppers at (978) 459-TIPS (8477). Callers may remain anonymous, but can receive up to $1,000 for information leading to an arrest.