San Francisco's public railway system hit by hackers

Some passengers on San Francisco's public railway enjoyed free rides during part of the Thanksgiving holiday weekend after hackers infiltrated hundreds of its workers' computers and email accounts.

The San Francisco Municipal Transportation Agency says it decided to open the gates at underground stations of its light rail system Friday and Saturday after detecting a "ransomware" attack aimed at stealing sensitive information in an attempt to be paid for the data's return. Regular fares were still charged for bus rides.

Agency spokesman Paul Rose says an investigation determined that the hackers didn't get any financial records or other potentially damaging information about the system's customers or employees.

As of late Monday afternoon, the agency was still trying to determine how much revenue it lost while giving free rides.