A gas tanker exploded on a motorway in a suburb of Mexico City, killing at least 20 people and injuring 36.
Television images showed damaged buildings and cars in the area of Ecatepec on Tuesday morning, about 14km north-east of Mexico City.
The explosion happened at about 5am local time on the highway between Mexico City and Pachuca.
The driver of the truck is under arrest in hospital, where he was being treated.
A BBC correspondent said the tanker was travelling north when it crashed into another vehicle. At least 30 houses and 20 cars were damaged.
Dozens of ambulances were sent to the scene.