An SUV speeding down South Waverly Wednesday crashed into an apartment building on 10th Street, killing all three adult passengers.

The SUV hit a car parked on the street and then into the building, where a resident was home. He was uninjured.

NBCDFW reports that the SUV belonged to neighbor Lucinda Esparza. Her son, Ernesto Esparza, saw her crashed car a few blocks from their home before police came to his door for help identifying her. Esparza said he didn’t know who the other two people in the car were.

It appears that the driver did not brake, as there were no skid marks.

Esparza told the TV station: “My mom does not drive fast, so it had to be a heart attack. It had to be she blacked out or something … But it’s just speculation because we don’t know.”