Uber Technologies Inc.’s self-driving vehicle wasn’t programmed to stop for obstructions in its path, including the pedestrian it struck and killed last March in Arizona, according to federal investigators.

Uber Technologies Inc. has found itself isolated a little more than a week after one of its self-driving SUVs hit and killed a pedestrian in Arizona.

The U.S. National Transportation Safety Board is gathering information about an accident involving a Tesla Inc. Model S sedan that rear-ended a firetruck on a freeway near Los Angeles on Jan. 22, the agency said.