The Chinese Ambassador to Pakistan is suspected to have been the target of the attack in the car park of the Serena Hotel, correspondents say.
He is understood to be in Quetta, the capital of Balochistan province near the Afghan border, but was not present at the scene at the time.
The Pakistani Taliban have claimed the attack, without giving details.
In recent months the group, and other militant organisations, have stepped up attacks in tribal areas near the border with Afghanistan.
