RIYADH, Saudi Arabia — A fuel truck exploded after hitting portions of a bridge Thursday in the Saudi capital, Riyadh, engulfing buildings and cars in flames and killing at least 22 people and injuring more than 110, witnesses and officials said.

The death toll was a significant increase in the number of reported casualties than in the first hours after the 7 a.m. explosion near the Saudi National Guard building in an industrial area in the city's eastern district. Columns of smoke could be seen rising from scene.

A security official told The Associated Press at least 22 people were killed and 111 were injured.

There was no immediate suspicion of terrorist links based on witness accounts, which suggested the fuel tanker exploded after striking part of a highway underpass.

Officials said rescue crews had not finished the search and the death toll was still not final.

All the officials and witnesses spoke on condition of anonymity because they were not authorized to talk to the media.

Civil Defense spokesman Capt. Mohamed al-Hammadi told the official Saudi Press Agency that the explosion occurred after the tanker spilled fuel, which expanded the area of the fireball. He described the damage as "significant."