BERLIN — German airline Lufthansa says 10 airport workers have suffered minor injuries from smoke inhalation when a vehicle pulling a jet to a gate caught on fire.

Lufthansa said that it was still not clear how the fire broke out Monday morning at Frankfurt Airport, but that the cockpit of the empty passenger aircraft was seriously damaged by the heavy smoke. The airline is currently assessing the extent.

The fire sent black smoke billowing into the air but airport traffic was not affected by the incident.