EL CAJON, Calif. -- A thin thief wearing sunglasses and a white baseball cap robbed an East County bank Tuesday, police reported.

The bandit, who was carrying a black duffel bag, handed a demand note to a teller at the Wells Fargo branch office in the 1200 block of Avocado Avenue in El Cajon about 10:45 a.m., Lt. Jim Redman said.

The clerk turned over an undisclosed amount of cash, which the robber put into the knapsack before walking out of the bank and fleeing to the east on foot.

Officers searched the area with help from a sheriff's helicopter crew but were unable to locate the thief, the lieutenant said.

Witnesses said the robber was a dark-haired, roughly 5-foot-7-inch white man who appeared to be in his 40s. He was wearing beige shorts, a blue shirt and sandals.