Police believe a suspected pipe bomb caused a mailbox explosion in Arvada early Thursday morning.
Arvada Police say they received four calls of a loud explosion heard around 2:30 a.m. in four block radius around 57th Avenue Kipling Street.
In the morning, police discovered the damaged US Postal Service blue mailbox 9500 block of Ralston Road.
Police and US Postal Service inspectors are on scene.
