Two successive bomb blasts have rocked the Pakistani garrison city of Rawalpindi, killing up to 24 people and wounding 66 others, police and military spokesmen have said.
The first blast on Tuesday happened on a bus carrying government workers, killing at least 15 people. A motorcycle bomb exploded minutes later, killing several others.
Military and government officials said the bus targeted was believed to be carrying Pakistan Atomic Energy Commission employees.
"It's terrorism because innocent people were killed in both blasts," Major General Waheed Arshad, a military spokesman, said.
Mohammad Hamid, a police officer, confirmed it was a bomb that tore through the bus in the city's Qassim market area.
"The explosive was on the bus," said Javed Iqbal Cheema, an interior ministry spokesman.
Kamal Hyder, Al Jazeera's correspondent in Islamabad, said Rawalpindi being a cantonment area with a large military presence was a high profile target.
He said questions would be asked as to how such attacks could be carried out in a city like Rawalpindi.
Hyder said it had been raining when the blasts took place and most people were indoors. "Otherwise, the casualties could have been much higher," he said.
Bus destroyed
The white-coloured 40-seater bus was completely destroyed and mutilated bodies lay on the street, a witness said.
Mohammad Tahir said: "There was a huge bang then I saw the bus in a mangled heap.
"Body parts were scattered across the road and there was blood everywhere."
The second bomb blast happened about three kilometres away in another market in the city, Cheema said.
Mohammed Afzal, a police official, said the dead and injured had been transported to different hospitals.
There was no immediate claim of responsibility for either bombing.
Several retaliatory attacks have rocked Pakistan after the government of General Pervez Musharraf crushed an uprising by armed Islamic students at Islamabad's Red Mosque in July.