Islamabad, Pakistan (CNN) -- Two bombs, both targeting buses carrying Pakistani Navy officials, went off within a half hour of each other in the southern city of Karachi on Tuesday, police said.
At least three people were killed and more than 30 wounded in the attacks, police said.
In the first attack, a bomb was planted on a motor bike and remotely detonated when one of the buses drove by, said city police official Raja Umar Khitab. Two Navy officials were killed and 17 others injured in the blast.
The attackers used a remote-controlled bomb for the second attack as well, said police official Sadiq Hussain. The bomb was planted by the side of the road. It killed one person.
Khitab said timings and targets of the blasts show that the same group is behind the attacks.
The attacks came five days after a blast at a gambling club killed at least 15 people and injured 40 others on Thursday.
In February, two small bombs targeted police stations in the city and exploded almost simultaneously -- but did not cause fatalities.
Karachi is the main commercial hub of Pakistan. It has seen a drastic increase in political, ethnic and religious violence in recent months.
It is widely believed that senior leaders of the Afghan Taliban use the sprawling metropolis as a safe haven, but rarely is violence in Karachi linked to the Sunni militant group.
Last year, Pakistani intelligence agents arrested Mullah Abdul Ghani Baradar, the Afghan Taliban's top military commander, in Karachi.