(CNN) -- The driver of a parade float involved in a deadly crash with a train in Midland, Texas, will not face charges, a city official said Friday.
The collision between a freight train and the parade float killed four veterans and injured more than a dozen other people, but no charges will be filed, Midland Public Information Officer Sara Higgins said.
It is unclear if charges against others will be filed. Once the police report is finalized, it will be sent to the District Attorney's Office, Higgins said.
An attorney representing Smith Industries, the owner of the truck that served as the float, identified the driver as Dale Andrew Hayden.
The accident happened on November 15 during the "Hunt for Heroes" parade to honor members of the U.S. military. The last flatbed truck in the parade was crossing the tracks when an eastbound Union Pacific train slammed into it, Midland police said.
The National Transportation Safety Board said the grade crossing warning system, which consists of a bell, lights and a gate, operated as designed, giving a 20-second warning of the train's arrival. But the truck entered the crossing and the gate lowered, tipping over flag stands on the float.
The board re-created the accident as part of an investigation.
Also Friday, a law firm representing some of the victims said it reached an agreement with Union Pacific to inspect the track and signal system. The firm will also inspect the locomotive and the train's horn, the firm Glasheen, Valles & Inderman LLP said.
"In the inspection, we will be testing the lights and gates system to determine why the system gave a short, 20-second warning and failed to give a 30-second warning as designed," the firm said. "We believe this information will help prove our claim that the railroad failed in its legal duty to maintain the warning time as it was designed."
An NTSB board member said the south traffic light at the grade crossing turned green 21 seconds before the train's arrival at the crossing, as designed, to allow traffic time to clear the crossing. At 20 seconds before the collision, the bells and lights on the mast activated, in keeping with the minimum time under federal law.
Those killed were identified as Marine Corps Chief Warrant Officer 3 Gary Stouffer, 37; Army Sgt. Maj. Lawrence Boivin, 47; Army Sgt. Joshua Michael, 34; and Army Sgt. Maj. William Lubbers, 43.
CNN's Mike M. Ahlers and Elwyn Lopez contributed to this report.