GREEN BAY, Wis. (WFRV) -- An overnight semi and tanker fire in Green Bay is under investigation. The fire department tells Channel Five that around 1:15 a.m. Wednesday morning, They found two semi tractors and trailers ablaze on Frog Street. With 18 firefighters responding, the fire was out in less than 30 minutes. The trucks were parked in a locked, unattended parking lot. There were no reported injuries.