Three bomb blasts including a suicide attack on Pakistani security forces in the commercial hub of Karachi killed four people on Wednesday, officials said, with the Taliban claiming responsibility.
Three paramilitary Rangers and one civilian were killed, while four other people were wounded.
In the first incident, two improvised explosive devices (IEDs) were placed close to a Rangers' checkpost in the busy North Nazimabad neighbourhood, killing one soldier and wounding three when they were detonated remotely.
The IEDs were installed in cement blocks, said senior police officer Amir Farooqi.
Later, a suicide bomber blew himself up at the entrance to the Rangers' headquarters in the same area of the city, killing two of the paramilitaries and a civilian security guard, and wounding another.
"The suicide attacker walked in and tried to enter into the gate when he was intercepted by the security officials and he blew himself up," Farooqi told AFP.
A spokesman for the Rangers confirmed the toll. "The Rangers personnel who spotted and intercepted the suicide bomber will be awarded the highest Rangers gallantry award," he added.
The injured were rushed to the nearby Abbasi Shaheed Hospital for treatment.
Tehreek-e-Taliban Pakistan spokesman Shahidullah Shahid claimed responsibility for the attacks.
"We carried out the attacks to take revenge for killing of our mujahideen in jails," he told AFP.
The Taliban regularly complain that their members, once incarcerated, are victims of extra-judicial killings by security forces.
Earlier this month a Taliban suicide attacker killed one of Pakistan's best-known police commanders, famed for his fearless work tackling militants in the city.
Karachi, a city of 18 million people which contributes 42 percent of Pakistan's GDP, has been plagued by sectarian, ethnic and political violence for years.
Pakistan has endured a bloody start to the year with 114 people killed in attacks in January, according to an AFP tally.
Prime Minister Nawaz Sharif's government has been under fire for failing to make a strong response to the upsurge in violence.