Four participants in summer sports camps at the University of Michigan had cash swiped from their rooms at South Quad residence hall this week, campus police said.

The thefts occurred Monday and Tuesday at the residence hall at 600 Madison Street, with two in the morning, one in the evening and one overnight, a campus crime alert said.

Police say the room doors may have been left unlocked, and there were no signs of forced entry.

In two cases, $10 was taken, and in the other two, $20 was taken, police logs show. The money was stolen from a purse, camera case and off a dresser, the log shows.

No suspects have been identified.

Students and camp participants were being urged to always keep doors locked and safeguard their belongings.

Anyone with information on the thefts is asked to call campus police at 734-763-1131.