A bombing claimed by Pakistani separatists killed 26 people including 14 soldiers at a railway station in the southwestern Balochistan province, a hospital spokesman said on Saturday.
The blast hit as passengers waited on a platform at the main railway station in the provincial capital Quetta.
Prime Minister Shehbaz Sharif said the attackers "will pay a heavy price", according to a statement from his office.
"Fourteen members of the army and 12 civilians were killed," said Wasim Baig, spokesman for Quetta's Sandeman Provincial Hospital, raising an earlier toll of 25 provided by police.
"Forty-six members of the security forces and 14 civilians were wounded," the spokesman added.
A journalist saw pools of blood and ripped backpacks at the scene, where a large metal sheet protecting passengers from the elements had been blown off.
Mohammed Oumer, one of the casualties, said he went to the station to get a train home to his village.
"But just as we arrived, there was the explosion and I found myself wounded and in hospital," he said.
Despite frequent attacks in Balochistan the toll of Saturday's blast was particularly high for the southwestern province, which borders Afghanistan and Iran.
The train station explosion hit at around 8:45 am (0345 GMT) and was claimed by the Baloch Liberation Army (BLA), one of the area's main separatist groups.
The attack "was carried out on a Pakistani army unit at Quetta railway station... after completing a course at the Infantry School," the BLA said in a statement.
The Associated Press of Pakistan, the official news agency, cited railway officials as saying the blast happened near the ticket booth when two trains were scheduled to depart.
At Quetta station, police said they were working to determine the cause of the blast.
"When we reached here, initially it appeared that some explosive had perhaps been hidden or left in the luggage. But now we think it may be a suicide bomber," Muhammad Baloch, a senior local police official, told journalists.
Firefighters, rescuers and passengers were working through abandoned luggage on the platform, guarded by heavily armed members of the security forces.
At the hospital, Mohammed Irfan had to identify two of his relatives killed in the bombing.
"As we woke up we found out there was an explosion," he said.
"Then we discovered that my uncle and another relative had gone to have tea at the station."
Agence France-Presse