NEWARK, N.J. (1010 WINS/ AP ) -- Authorities say a fire hydrant is missing and someone stole equipment while firefighters battled a 5-alarm blaze in Newark.

Newark's rescue squad noticed handheld radios, a hydrant wrench and a tool used to pry open doors and floors were missing after the fire was brought under control Wednesday.

Firefighters also found a hole in the ground on the corner of South 20th Street and 13th Avenue where a fire hydrant was supposed to be.

The fire destroyed three buildings and damaged four others. Twenty firefighters went to the hospital for treatment of heat exhaustion and minor injuries.

Firefighters say the fire started in one vacant home and then jumped to the one next door.

The cause is under investigation.