LOS ANGELES, California (CNN) -- The California Public Utilities Commission banned texting on the job Thursday after it was shown that a Metrolink train engineer involved in last week's deadly collision near Los Angeles sent text messages from his cell phone.
It was unclear what 46-year-old Robert Sanchez was doing at the time of the crash Friday. The National Transportation Safety Board is investigating claims that he was sending text messages when his commuter train slammed into a Union Pacific freight train in Chatsworth.
Twenty-five people were killed, including Sanchez, and at least 130 were injured.
Investigators subpoenaed the phone records of the engineer and determined that he "had sent and received text messages on the day of the accident, including some while he was on duty," according to an NTSB statement Wednesday.
Investigators were trying to determine at what time the messages were sent.
The commission's emergency order passed unanimously Thursday.
In pushing for the ban, Commission President Michael Peevey said that cell phone use by engineers "may have been a factor" in train accidents this year in San Francisco and Sacramento, California. He did not elaborate on details of those incidents.
Thursday's order is temporary until the state commission decides whether to make it permanent.
Metrolink prohibits cell phone use by engineers on the job, but Peevey emphasized that there is no federal or California regulation barring cell phone use by engineers while trains are moving.
The NTSB had determined that the brakes on the Metrolink train were not applied before the collision and that stop signals at the scene were working properly, said Kitty Higgins, an NTSB member assigned to the investigation. Metrolink has said its train, carrying about 220 passengers, failed to stop for a red signal. Watch expert tell what it's like to drive a train »
Twenty-four bodies were found at the scene after the head-on collision during rush hour Friday in the northwest Los Angeles suburb. A 25th victim, a man in his 50s, died at a hospital. More than 130 people were injured.
The agency has said it also has been in contact with the two teenagers who told a local television station they were exchanging text messages with the engineer just before the crash occurred.
Higgins said investigators have interviewed the Metrolink train conductor, who had worked with Sanchez since April. The conductor "had no issues of his time working with the engineer and on how the engineer operated the train," she said. Watch as callers to 911 describe the crash »
The engineer took a two-hour nap during his midday break on the day of the collision, the conductor told investigators.
Sanchez was a subcontractor who worked for another company.