SANTA FE, Texas -- A train pulling tankers of hydrogen fluoride and other chemicals derailed near the State Highway 6 and Galveston County line. For a while, a 2-mile stretch of highway was shutdown and a handful of families were foreced to evacuate their homes. They were allowed back to area on Sunday morning.

A railroad spokeswoman said that 12 tank cars left the tracks near Mustang Road not far from the county line at about 5 p.m.

None of the tankers carrying chemicals leaked their contents, but a pair of cars that had water in them did spill said Santa Fe Fire and Rescue Chief Tommy Anderson.

The chief said the homes in the immediate vicinity to the derailment were evacuated and the road was closed as a precaution because of the dangers posed by the cars containing hydrogen fluoride. Most of the Union Pacific rail cars were classified as empty, but carried residual amounts of the chemical, which could be up to 10 percent of the tank car's capacity, said Anderson.

What concerned officials about the hydrogen fluoride is that if any had leaked and came in contact with water it would immediately convert into hydrofluoric acid, which is highly toxic. On its own, hydrogen fluoride has a strong, irritating odor and can cause respiratory problems.

No one was hurt in the derailment. In addition to the five residences that were evacuated, residents of another 30 homes nearby were restricted inside their homes.

Those not home at the time of the derailment had to be escorted back to their residences.

The railroad company was working to find temporary housing for those displaced by the derailment.

Only two of the estimated 12 cars that spilled off the tracks and into a parallel ditch contained hydrogen fluoride. One of the derailed cars was full and contained difluoroethane said Union Pacific spokeswoman Raquel Espinoza.

She said nine of the cars that derailed turned over on their sides, the other three remained upright.

The train was traveling north along the track that runs through Santa Fe and is owned by Burlington Northern-Santa Fe Railroad. Espinoza said the train left Angleton and was traveling to Houston.

Heavy machines including bulldozers, backhoes and land movers arrived at the derailment site at about 7:30 p.m. to begin the process of righting the derailed tankers.

The Texas Commission on Environmental Quality was also at the site to determine if any environmental risk existed. A company specializing in air quality measurements was also called in to check for any releases.

The place of the derailment was located within Galveston County between Santa Fe and Alvin. The train had just taken a curve at Mustang Road when it left the tracks.

From photos provided by Santa Fe Fire and Rescue, it appeared that the train derailed at a switching station. Portions of the steel rails of the track were bent like wet noodles and about a quarter of a mile of track appeared damaged.

Many of the tank cars that came off the tracks slid down an incline into a large drainage ditch that runs along the tracks.

Anderson said he hoped the road would reopen between midnight and 1 a.m. on Sunday.