Three consecutive explosions claimed by a little-known separatist group killed four people including two soldiers in Pakistan's southern province of Sindh on Friday, officials said.
At least a dozen people were also injured.
Shadowy secessionist organization the Sindhudesh Revolutionary Army, which wants the province to break from the Pakistani federation, said it carried out the attacks.
One of the blasts was in Karachi, Pakistan's largest city and the capital of Sindh, where a civilian died and eight others including a paramilitary soldier were injured.
That explosion was outside a centre for distribution of government cash handouts, and police believe the target was a vehicle of the Sindh Rangers paramilitary force parked outside.
The second blast was reported in Ghotki district, 500 km north of Karachi, where two Rangers soldiers died along with a passerby, local police chief Furrukh Ali told Reuters.
The third blast took place in Sindh's Larkana district, where no casualties were reported.
The Sindhudesh Revolutionary Army has carried out low-intensity attacks in the past, including blowing up train tracks, but its separatist fight has been less violent than that of neighbouring Balochistan province.
"Sindhudesh Revolutionary Army claims the responsibility of Karachi, Ghotki and Larkana attacks," it tweeted, without giving more details.
The Rangers, a wing of the Pakistan Army, have been deployed around Pakistan and played a prominent role in crackdowns on terrorists and criminals in Karachi.
Sindh's Chief Minister Murad Ali Shah ordered an inquiry into Friday's violence.