LOS ANGELES (AP) -- The state's top rail safety regulator said Monday he would seek an emergency order banning train operators from using cell phones, as federal investigators sought to determine whether the engineer of a commuter train was text messaging before a crash that killed 25 people.

Michael Peevey, president of the California Public Utilities Commission, said some railroad operators have policies prohibiting the personal use of cell phones, but they're widely ignored. ""Our order would make it the law and we'll go after violators. We owe it to the public,"" he said.
The collision on Friday between the Metrolink commuter train and a Union Pacific freight train was the deadliest rail disaster in the U.S. in 15 years. Metrolink has blamed its engineer for not heeding a red light signal designed to prevent such wrecks.
Federal rail investigators said Monday tests at the crash site showed the signals are working properly and there were no obstructions that may have prevented the engineer from seeing the red light.
The National Transportation and Safety Board said it will now review whether engineer Robert Sanchez was text messaging. Investigators did not find a cell phone belonging to Sanchez in the wreckage, but two teenage train buffs who befriended him told KCBS-TV that they received a text message from him a minute before the crash.
Metrolink prohibits rail workers from using cell phones on the job, but there is no existing federal regulation regarding the use of cell phones by railroad employees on the job, Federal Railroad Administration spokesman Steven Kulm said.
NTSB board member Kitty Higgins said her agency issued a subpoena Monday to get the engineer's cell phone records. She said Verizon Wireless has five days to respond to the subpoena request.
As NTSB experts prepared to conduct a simulated crash test on Tuesday, some commuters — many wary and emotional — returned to the rail line on the first day of service after the accident.
Mayor Antonio Villaraigosa tried to reassure them the trains are safe.
""I want to dispel any fears about taking the train,"" he said. ""Safety has to be our No. 1 concern, and while accidents can and do happen, taking the train is still one of the safest and fastest options for commuters.""
About a dozen bouquets were strung the length of the loading platform at the Simi Valley station as passengers boarded buses and were shuttled to the Chatsworth station, bypassing the tracks still being cleared of wreckage.
Regular commuters said the train load was much lighter than usual.
The NTSB said the commuter train, which carried 220 people, rolled past stop signals at 42 mph and forced its way onto a track where a Union Pacific freight was barreling toward it. Higgins said the commuter train engineer, who was among the 25 dead, had failed to stop at the final red signal. The crash also injured 138 people.
The collision occurred at a curve in the track just short of where a 500-foot-long tunnel separates the San Fernando Valley neighborhood of Chatsworth from Simi Valley in Ventura County.
Jerry Romero, who normally takes the Metrolink home but skipped it Friday to pick up a bicycle, said he was disturbed by texting reports.
""That would be pretty disturbing in respect to what we're going through as a society, this fascination we have with gizmos,"" he said.
In 2003, the NTSB recommended that the Federal Railroad Administration regulate the use of cell phones by railroad employees on duty after finding that a coal train engineer's phone use contributed to a May 2002 accident in which two freight trains collided head-on near Clarendon, Texas. The coal train engineer was killed and the conductor and engineer of the other train were critically injured.