MEXICO CITY – A gas truck explosion that generated a “shock wave” in Mexico City on Wednesday killed at least four people and left 90 injured, according to the city prosecutor’s office.

Those who were injured were taken to hospitals in the city, many in a a serious condition, Mexico City Mayor Clara Brugada said in a press conference.

Images shared on social media showed flames shooting high into the air as people screamed and ran from the scene in the Iztapalapa borough. Another video showed large plumes of smoke billowing from the truck as emergency workers tried to extinguish the fire.

The explosion generated a “shock wave” that damaged 32 nearby vehicles, the Mexico City Prosecutor’s Office said late on Wednesday.

According to authorities, the explosion occurred after the vehicle carrying 49,500 liters of gas – known in Mexico as “pipas” – overturned by a highway in the Puente de la Concordia area.

An investigation was underway “to establish accountability and ensure comprehensive care for the victims and their families,” the prosecutor’s office said.

“Forensic experts... are working at the scene to gather initial evidence and determine the cause of the incident,” said the prosecutor’s office.

Other agencies would also be involved in trying to determine whether the company that owned the tanker had complied with regulations.

The driver’s condition is also being investigated.

The fire has been extinguished, Brugada said, but cooling efforts were continuing late Wednesday. – CNN