BIXBY, Okla. >> Federal authorities said today that they are no longer investigating a pipe bomb explosion that damaged a northeast Oklahoma Air Force recruiting station as a possible act of domestic terrorism, adding that the blast could be the work of a disgruntled employee or a prank.

FBI agent Jessi Rice said the explosion in the Tulsa suburb of Bixby is not being called domestic terrorism because investigators have not determined a motive and have not identified a suspect. Rice said the blast currently is a criminal investigation into the use of an explosive device.

“We don’t know if it was a disgruntled employee, an act of terrorism or someone playing games,” Rice said at a news conference.

A device was set off around 10:30 p.m. Monday in front of the recruiting center, which was closed, federal authorities said. No one was hurt.

Earlier today, a spokeswoman for the Bureau of Alcohol, Tobacco, Firearms and Explosives said the blast was being treated as a possible act of domestic terrorism out of “an abundance of caution,” because of its proximity to the recruiting office.

The Air Force recruiting station is in a commercial area that also houses restaurants, financial planning firms and other businesses. A movie theater is nearby.

The door of the recruiting center was blown off in the explosion and landed in a parking space in front of the storefront and soot-covered windows. Two workers from a glass repair business were replacing the shattered door with a new one by late this morning.

Rice said agents were still scouring the area for surveillance cameras that might show someone putting the device in place or a vehicle containing suspects. A witness said a motorcycle was seen in the area around the time of the blast.

Agents also are looking into a possible connection between the explosion and recent vandalism of vehicles in the parking lot of a nearby Air Force National Guard center, Rice said.

The aftermath of the blast rattled some business owners near the recruiting center and bystanders who gathered around the site.

“We just opened (on Monday) and we get the fireworks,” said Dale Barnett, co-owner of Barnett Music Exchange, located four storefronts from the recruiting station.

Linda Allen, who lives in Tulsa, said it concerns her that the explosion happened so close to home.

“I’m worried if there is a safe place in (the Tulsa area) anymore,” she said.

Associated Press writer Ken Miller contributed to this report from Oklahoma City.