WASHINGTON—Safety officials investigating the cause of a Tesla Model S crash that killed two men in Texas last month said that testing suggested the vehicle’s automated steering system was “not available” on the road where the accident occurred. But the car’s cruise-control function could still have been in operation, the National Transportation Safety Board (NTSB) said in its preliminary report on Monday. The report drew no conclusions about the cause and circumstances of the fiery April 17 crash in a suburb of Houston. The NTSB and local police are still investigating. Local police have said they believed the crash occurred with no one in the driver’s seat, raising questions about Tesla’s driver-assistance systems. The NTSB said footage from the owner’s home security cameras showed the owner entering the driver’s seat and the passenger entering the front passenger seat. The accident has raised fresh questions about the safety of Tesla’s “Autopilot” …