Pakistani security forces exchanged gunfire on Wednesday with hundreds of terrorists as they sought to free about 300 hostages aboard a train in the country's rugged southwest, officials said.
Security forces were being cautious as officials said the hostages were surrounded by terrorists wearing vests loaded with explosives.
Government spokesman Shahid Rind said Pakistani forces were being backed up by helicopters in the remote region and described the attack as "an act of terrorism".
At least 30 terrorists have been killed and security forces rescued 190 of the approximately 450 people who were on the train when it was hijacked on Tuesday as it entered a tunnel in Bolan, a district in restive Balochistan province.
It was the first time terrorists have ever carried out such an attack.
The Baloch Liberation Army terror group has claimed responsibility for the attack, saying it was open to negotiations to swap prisoners. So far, there has been no response from the government to the offer from the terrorists.
The BLA regularly targets Pakistani security forces, but has also in the past attacked civilians, including Chinese nationals working on projects related to the China-Pakistan Economic Corridor, or CPEC.
TRT Global - The train, carrying women and children, was travelling from Quetta to Peshawar when it came under attack, but district police officer Rana Dilawar says around 350 passengers are safe, and a relief train is on the way.
Authorities said the rescued so far included women and children, while an undisclosed number of security personnel have been killed, according to three security officials who spoke on condition of anonymity as they were not authorised to speak to media.
According to the officials, the train was partially inside a tunnel when the terrorists blew up the tracks and immobilised the engine and its nine coaches.
The driver was critically wounded by gunfire and guards aboard the train were attacked, although the officials gave no details on the number of guards who were aboard or their fate.
Rescued passengers were being sent to their home towns and injured were being treated at hospitals in Mach district in Balochistan. Others were taken to Quetta about 100 kilometres (62 miles) away.
The train that was travelling from the provincial capital, Quetta, to the northern city of Peshawar when the attack took place.
Trains in Balochistan typically have security personnel on board as members of the military frequently use trains to travel from Quetta, the capital of Balochistan to other parts of the country.
Terrorists have attacked trains in the past but have never managed to hijack one.
