"There are at least 20 dead," the local official quoted in a TV news report.
The death tolls could not be confirmed by both national railways company SNCB and the track operator Infrabel, even as Anne Woygnet of SNCB is involved in making a list of those 'seriously' injured.
However, Infrabel spokeswoman Fanny Charpentier said that the police would place the probable toll to a dozen.
"The collision was brutal, the train didn't brake. Wagons have been turned over, lots of people are in shock," a passenger said.
The incident which took place at rush hour has led to a serious disruption of services.
Operators of Thalys and Eurostar high-speed train services said that services in and out of Brussels would be disrupted.
Informing that three trains were involved in the accident, Thalys has advised passengers to reschedule their traveling plans.
Meanwhile, Eurostar has warned passenger that services are likely to remain disrupted the entire day.