"China strongly condemns the terrorist attack on a church in Quetta, Pakistan", China's Ministry of Foreign Affairs said in a statement that comes a day after nine people were killed in a suicide attack at the Bethel Memorial Methodist Church on Quetta's Zarghoon Road.
Balochistan Home Minister Sarfraz Bugti said around 250 people normally attend the church on Sundays, but the congregation had swelled to around 400 because it was close to Christmas.
One attacker detonated a vest laced with explosives near the door to the church's main hall.
From the CCTV footage one can make out the police officer firing his gun from behind a tree without caring for his own life as he attempts to stop the militants dead in their tracks and prevent them from carrying out an attack on a large scale.
Abdur Razzaq Cheema, Quetta police chief, said authorities are looking for another two suspects.
Islamic State claimed responsibility for the attack, the group's Amaq news agency said, but provided no evidence for the claim. Muslim extremists have targeted Pakistan's small Christian minority in the past.
On Saturday, Pakistani children lit lamps to mark the third anniversary of the Peshawar school attack in the city.
A young girl in a white dress sobbed as she recounted the attack to Geo television, saying many people around her were wounded.
Two people flee after Sunday's attack on worshippers at the Bethel Memorial Methodist Church in Quetta.
Another 15 people were killed at two churches in Lahore when suicide bombers struck each of them.
Two women were among the dead, and 10 women and seven children were among the injured, hospital officials said.
Aqil Anjum, who was shot in his right arm, told The Associated Press he heard a blast in the middle of the service, followed by heavy gunfire. "It was chaos. Bullets were hitting people inside the closed hall".
Dozens of Christians gathered outside a nearby hospital to protest the lack of security.
Several gunmen have reportedly attacked a Christian church in the southern Pakistani city of Quetta.