CHICAGO (CBS) — A man armed with a knife has robbed two Lake View fast-food restaurants in the last week.

The man, thought to be between 25 and 35 years old, demanded cash while wielding a knife in separate armed robberies, police said.

The first incident happened about 11 p.m. on Feb. 8 in the 1000 block of West Belmont, and the second was reported about 4:45 p.m. on Saturday in the 3700 block of North Clark, the alert said.

The robber, described as a slim white man weighing about 160 pounds, was wearing a black North Face jacket in the Belmont robbery, police said.

In the Clark robbery, he wore a drab green or olive jacket over a blue hooded sweatshirt, with blue jeans that were bleached or stone-washed in the thigh sections.

Police urge business owners to keep their video surveillance systems in good maintenance.

Anyone with information should call Area North detectives at (312) 744-8263.