The first two blasts -- one caused by a roadside bomb and the other from a motorbike packed with explosives about 30 feet (10 meters) away -- happened within a minute of each other in downtown Kandahar, said Deputy Provincial Police Chief Fazel Ahmad Sherzad. About two hours later, a third blast struck north of the city.
The looming offensive and a surge in militant attacks -- on local officials, aid workers and contractors for U.S. development projects -- has left Kandahar's half-million inhabitants increasingly terrified.
"The security in this city is deteriorating," said Enayutullah Khan, 43, a rickshaw driver. "People leave their homes only to find food for their children. Otherwise we don't leave the house."
Rangina Hamidi, who runs a Kandahar-based handicrafts business that employs about 200 women, said many of her workers had been too frightened to come to work in recent days.
"It's very scary. We don't know what is happening," said Hamidi, whose employees sew embroidered clothing, tablecloths and shawls.
Kandahar is the largest city in southern Afghanistan and the birthplace of the Taliban, which still has considerable support here. A U.S.-led operation planned for this summer aims to clear Kandahar of Taliban fighters and break the grip of warlords who have allowed the fighters to slip back in.
President Barack Obama has ordered 30,000 more troops into Afghanistan, in part to back up the Kandahar offensive. The operation will be a critical test of the Afghan war.
But the Taliban have launched increasingly deadly attacks ahead of the offensive. Since April 12, at least 20 civilians have been killed in Kandahar, including children. Aid workers also have been targeted.
Monday's first two explosions, which killed two civilians and injured one police officer and one civilian, happened while a convoy of police vehicles was passing by, the Interior Ministry said.
One of the explosions went off near a car belonging to Sherzad, the deputy police chief, but he was not inside the vehicle at the time. Another policeman was injured in the blast in the city's north.
Also Monday, Eric Laroche, the World Health Organization's assistant director-general for health action in crises, urged that more be done to protect the health of millions of Afghans still vulnerable to disasters like earthquakes and combat.
"Much has been achieved in recent years to expand health care in many parts of the country, but we still see today that many Afghans remain extremely vulnerable to a wide range of humanitarian emergencies, and more needs to be done to protect them," Laroche said in a statement, urging that more medical personnel and clinics be made available across Afghanistan, particularly in remote areas.
On Sunday, meanwhile, one Afghan police officer was killed and another was wounded during an attack on a militant compound in the Wordoch district of Badakshkhan province northeast of Kabul, according to an Interior Ministry statement released Monday. The statement said two militants were killed in the operation. During a search of the compound, authorities found explosives and eight different kinds of roadside bombs.
Also Sunday, government forces on a mission to eradicate poppies in eastern Nangrahar province came under fire, said Ghafor Khan, a provincial police spokesman. During the gunbattle three Afghans -- one from the Afghan Army and two from the border police -- were killed. Nine more members of various Afghan forces were also injured. Six Taliban militants were killed in the fighting and 12 were injured, Khan said.
The area is now under government control, and the forces destroyed about 200 acres (80 hectares) of poppies.