SLIPPERY ROCK — A robbery at NexTier Bank on Main Street late this morning rattled the downtown area as state and borough police searched for the robber, who was said to be on foot.

The robbery occurred about 11:30 a.m.

A sign on the bank's door said because of the emergency, the bank was closed. This is the fourth robbery in Butler County in the last few weeks.

State and borough police cars surrounded the bank as a helicopter also was overhead. After spending about two hours at the bank, the police spread out into the neighborhood.

One state trooper was walking from business to business to ask if anyone had seen the robber or any suspicious people. Other police drove through the borough on different streets.

No other information was immediately available.