PARIS  A head-on collision between trains outside Brussels during the morning rush on Monday killed at least 18 people and injured 80, a police spokesman said, in Belgium’s deadliest railroad accident in more than 25 years.

Rescue workers were still pulling bodies from the wreckage on Monday evening, and the police estimated that the death toll could rise as high as 25. All of the survivors had been evacuated, said the spokesman, who declined to be identified, citing police policy.

The cause of the accident, which occurred around 8:30 a.m. in snowy conditions in the village of Buizingen, near Halle, about 10 miles southwest of Brussels, remained unclear.

Lodewijk De Witte, the governor of the province of Flemish Brabant, told reporters on the scene that one of the trains appeared to have disregarded a signal to stop, but the police spokesman would not confirm that.