Pittsburgh - A dump truck driver from Ohio purposely crashed his vehicle through the security gate of the FBI's offices in Pittsburgh on Tuesday, injuring himself but no one else, an agency spokesperson said.The truck was moving erratically and had disregarded stop signs and lights before a city police officer pulled it over about 11:00 near the FBI building on the city's South Side, Special Agent Gregory Heeb said.The driver then told the officer he intended to ram the FBI gate - but didn't explain why - before speeding away and doing just that, Heeb said. The truck was disabled by security barriers that are meant to prevent vehicles from driving into fenced-in office complex. Agents checked the truck for bombs and found nothing.Heeb said the truck was also registered in Ohio, but the driver's name and the name of the vehicle's owner weren't immediately released.The FBI was working with police to determine what charges to file. A Pittsburgh police spokesperson didn't immediately comment.The US attorney's office in Pittsburgh confirmed it has been contacted. That office would prosecute any federal charges that are filed."We don't know yet how it's going to play out," Heeb said. "Obviously the biggest focus for us is going to be his mental state and what was his history."The truck driver was the only one injured. He was taken to a Pittsburgh hospital, though authorities didn't say which one and his condition was not immediately available.