The attack comes a week after Tehrik-i-Taliban Pakistan ended a ceasefire with the government this week.
A suicide bomb blast by Pakistani Taliban militant group in the country's southwestern city of Quetta has targeted a police patrol, killing three people and wounding 28.
"A bomb blast that targeted a police patrol wounded more than 30 people, including 15 police," a police official, Abdul Haq, said on Wednesday.
"Out of them, a policeman, a woman and a child died."
The explosion, claimed by the Pakistani Taliban militant group, or Tehrik-i-Taliban Pakistan (TTP), came after the group ended a ceasefire with the government this week.
The patrol had been guarding a polio vaccination team at the time of the suicide blast, he added.
Militants in Pakistan often target polio vaccination teams, in the belief that the immunisation effort is a Western tool to spy on them.
Quetta is the capital of Pakistan's province of Balochistan bordering Afghanistan and Iran, where the insurgents operate.
TTP's attacks in Pakistan
On Monday, the TTP group declared an end to a shaky ceasefire with Islamabad declared over the summer and ordered nationwide attacks to resume.
The group were at the height of their power in Pakistan between 2007 and 2009, when they held sway over the Swat valley just 135 km north of Islamabad.
They were pushed into Afghanistan by an army offensive after perpetrating a barbaric schoolhouse bombing that killed nearly 150 students in 2014.
Although the Taliban in Afghanistan have encouraged Islamabad and the TTP to reach a peace agreement through dialogue, talks amid a ceasefire between the two sides that started in May proved futile.