Fire that closed Route 100 in Lehigh County is under investigation.

Firefighters respond to a fire at a Fastenal fulfillment center in the 400 block of South Route 100 in Upper Macungie Township on Wednesday morning, May 29, 2024. (Jayson Wagner/Special to The Morning Call)

A fire at a Lehigh County business building Wednesday morning remains under investigation.

According to Upper Macungie Township police, firefighters were called to Fastenal, 431 S. Route 100, around 5:45 a.m. for a report of a fire. The second-alarm fire caused damage to the building, according to Lt. Peter Nickischer.

Photos of the fire posted on social media showed smoke rising from the building as firefighters battled the blaze. The site is a fulfillment center for Fastenal, a supply chain solutions company and wholesaler, the company’s website said.

Nickischer said the building was unoccupied at the time and no one was injured. Route 100 was closed in the fire area while emergency crews were on site. The roads were reopened around 9 a.m.

Parish police and a state police fire marshal are investigating the fire. Anyone with information is asked to contact police at 484-661-5911.