A car bomb blast on Wednesday night ripped through a hotel's parking area in the southwestern Pakistani city of Quetta, killing five people and wounding 12, local officials said.

According to a statement of the Chinese embassy in Islamabad, Chinese Ambassador to Pakistan Nong Rong was leading a delegation on a visit to Quetta on the same day.

"When the attack occurred, the Chinese delegation was not in the hotel. Till present, no reports of casualties of Chinese citizens in the attack have been received," it said.

Pakistan's Interior Minister Sheikh Rasheed Ahmad described the attack in Balochistan Province as "an act of terrorism".

Provincial Home Minister Ziaullah Lango said the envoy was fine.

Calling the blast a terrorist attack, China's Foreign Ministry spokesman Wang Wenbin confirmed on Thursday that the Chinese delegation was not present when the bomb detonated.

"China strongly condemns this terrorist attack, and we are saddened by the innocent victims," he said.

Gu Wenliang, agriculture commissioner at China's embassy in Pakistan, told the Chinese newspaper Global Times that the bomb had detonated 10 minutes before their expected return.

Khuda Baksh, a guard at the hotel, said: "I was walking through the car park when I heard a sudden loud sound and the earth shook under my feet. Everyone was running for their lives before I lost consciousness."

The Pakistan Taliban claimed responsibility for the attack, but the claim has not been officially confirmed. They said Pakistan security officials were the target of the blast.

Wednesday's attack came after extremist-linked violence in Pakistan has largely been reduced in recent years.

"We will not allow this monster to reemerge," tweeted Pakistan's Prime Minister Imran Khan.

There was a threat alert in Quetta and other major cities after suspicious calls were intercepted, and security was on high alert including in cities in Balochistan Province, said Rasheed.

Lango said a bomb disposal squad reached the blast site to investigate the incident, and based on their initial probe, nearly 40 kilograms of explosives were used in the attack.

The hotel is next to the Iranian consulate and the provincial parliament building. Quetta is the capital of Balochistan Province, which borders Iran and Afghanistan.

Agencies and Xinhua contributed to this story.