A gas tanker's container came loose and exploded on a highway north of Mexico City, landing between homes and setting fires that killed at least 24 people and injured dozens.
The blast rocked the suburb of Ecatepec before dawn, injuring at least 36 people and damaging some 15 cars and 40 homes, officials said. Ten children were among the dead and eight more were wounded.
Nearby buildings, cars and trucks caught fire after the tanker exploded at around 5:30 am in the poor community of San Pedro Xalostoc, which is part of the municipality of Ecatepec.
Several sheep, rabbits and dogs belonging to residents lay dead around the neighborhood.
One of the truck's two containers cut loose and fell on the community below, said Transport Minister Gerardo Ruiz Esparza. An AFP reporter saw the tanker on a patio between two homes, surrounded by the charred remains of a handful of cars.
The first tanker was still attached to the cab of the truck on the road, and authorities pumped gas out of it to prevent another disaster. Officials were investigating the cause of the accident.
A couple and their two children, aged six and 12, were killed when the loose tanker landed near their home, according to the father's cousin.
"I ran out and took refuge on nearby roads after I heard the thunderclap," 45-year-old Humberto Zedillo told AFP.
"I saw the house of my relatives in flames and when I returned the forensic experts were removing the bodies of my relatives."
Firefighters sifted through the rubble for any more victims after the blast left behind the charred remains of vehicles, flung road cement barriers off the highway and sent smoke billowing from buildings.
The death toll rose throughout the day and a spokeswoman for the federal highway department said there were 24 people dead late Tuesday. Officials said 13 of the injured were in serious condition.
The driver survived the accident and was "detained in a hospital where he is receiving medical treatment," Mexico state public safety secretary Salvador Neme wrote on Twitter.
Transport Minister Gerardo Ruiz Esparza said the truck's and the driver's paperwork were in order. The truck belonged to a company named Termogas.
The highway, which links the capital to the central city of Pachuca, gradually reopened hours after the accident.
President Enrique Pena Nieto expressed his condolences to the families of the victims and ordered his government to take measures to improve safety around the highway.
More than 24,000 people die in road accidents in Mexico each year, according to official figures, and experts have warned of the dangers posed by trucks carrying hazardous materials.
Trucks carrying dangerous substances were involved in almost 1,200 collisions between 2006 and 2009, killing 196 people and injuring 838 others, according to a study by the state-affiliated Mexican Transport Institute.
The transport minister said the government would study the need for more restrictive circulation rules for cargo trucks, noting that Mexico has less stringent weight and size restrictions than developed nations.
In April last year, 43 people died in the eastern state of Veracruz when a double-trailer truck lost its rear trailer and slammed into a bus packed with farmers.