Police reported seven blasts at various areas throughout the city -- at least one of them near a police station. A motorbike, a bicycle and a truck were involved in three of the bombs.
Pakistan's ARY One World television reported that seven blasts in less than three hours killed two people and wounded at least 50, including 15 children.
Nobody claimed responsibility in the immediate aftermath of the explosions.
The Associated Press reported the blasts happened in residential and commercial areas.
The state-run news agency Associated Press of Pakistan (APP), on its Web site, reported a senior police officer saying the blasts "were of low intensity and their objective seems to be to create panic."
APP said one blast was in a junk market; another near a gas pump; one was in a light truck; another was near a school; and one was near a roundabout.
The explosions come a day after a suicide bomb attack at a rally in the capital, Islamabad, killed 17 people.
In recent months, other parts of the country, including Lahore and Islamabad, have seen numerous attacks, but Karachi has been in a relative period of calm.
