SAN DIEGO -- Authorities held two robbery suspects Tuesday but sought two others following a heist at an Old Navy store in Mira Mesa.

Four robbers wearing hooded sweatshirts entered the store at 10655 Westview Pkwy at 7:05 p.m. Monday, said San Diego police Sgt. Diane Wendell.

They approached the manager behind the counter, displayed a handgun and demanded that cash be placed in a backpack, Wendell said.

The robbers fled in different directions after they noticed numerous citizens on cell phones, Wendell said.

Police set up a perimeter search and found one of the suspects in a parking lot 10 minutes after the robbery, and another at a construction site about 90 minutes after the incident, Wendell said.

A gun was recovered during the search, and the investigation is ongoing, Wendell said.