Dallas police are investigating what shattered the cab window of a fire truck Friday morning.
No one was hurt in the incident that occurred on I-30.
At first it was believed to have been a rock, then a gunshot, according to The Dallas Morning News.
But, later police denied the shattering was caused by a gunshot, the paper reported.
The vehicle out of Dallas Fire Resue Station 19 was damaged in the 9:45 a.m. incident that remains under investigation.