The deadly accident may also rekindle questions about China’s transportation infrastructure, which has expanded at a heady pace in recent years. In August, a 330-foot-long ramp section of a bridge in the northeast collapsed 100 feet to the ground, taking four trucks with it, resulting in three deaths. That was the sixth major bridge in China to collapse since July 2011, according to a Xinhua report at the time.

None of the reports about the latest bridge accident raised questions about the quality of construction. One initial news report said at least 26 people were killed, but officials on the scene later dismissed that number as too high, according to the Web site of People’s Daily, which said about 11 people were injured.

Images on Chinese television and news Web sites showed rescuers clambering over the shattered remains of trucks that had plunged to earth, with part of one truck hanging off the severed section of the bridge. Reports from the scene said 10 to 25 vehicles fell off the bridge.

“A number of vehicles were crushed under the fallen bridge section, adding to the difficulties of the rescuers,” said a report on China Central Television.

After the explosion, the Ministry of Public Security convened a video conference with police officials across the country, urging them to tighten controls on the production and transportation of fireworks, according to the Web site of Legal Daily, a state-run newspaper.