RAPID CITY, S.D. (AP) — Police in Rapid City say they're investigating the city's fourth casino robbery in two weeks.

Officers were called to a casino on Mount Rushmore Road about 9 a.m. Thursday after a suspect wearing a black hooded sweat shirt entered through a back door, demanded money and fled with cash. He was last seen riding a bicycle east through the alleyway behind the business.

Police say they don't believe that Thursday's suspect is the same person suspected in other recent robberies under investigation.

One person was arrested in one of the robberies, an Aug. 10 incident on Saint Patrick Street.

Copyright 2015 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

More From KXRB