U.S. auto safety regulators are investigating a Waymo autonomous vehicle that struck a child near a school in Santa Monica, California, the second recent probe to examine the behavior of the Alphabet Inc. unit’s robotaxis near children. Waymo, which announced the incident earlier, said the child sustained minor injuries, according to the regulator. Related: NTSB Opens Probe Into Waymo Robotaxis Passing Stopped School BusesThe episode adds to federal scrutiny of how Waymo’s autonomous robotaxis handle encounters near young pedestrians. NHTSA said it would examine whether the Waymo vehicle “exercised appropriate caution” and the automated driving system’s intended behavior in and around school zones. Top photo: Waymo vehicles at a charging station in Santa Monica, California.