GLEN ROCK - Thieves stole four defibrillators from sports fields in the town of Glen Rock, authorities say.

Police say the units were stolen sometime between Thursday evening and Sunday morning.

The town purchased the defibrillators in 2012 with money donated by parents. They were purchased to improve the safety of student athletes and fans.

Glen Rock police say that they need the units returned because it is a safety issue to not have them.

Police are reviewing surveillance video in the area to see who may have taken them. The machines cost about $6,000.

The Glen Rock mayor is offering a $1,000 reward for their return.