Three near-simultaneous blasts killed two women and wounded 21 people in Kathmandu on Sunday, Nepal's police said, the first since a peace process ended a Maoist revolt in the Himalayan nation in May last year.
The attacks came less than three months before the impoverished nation, sandwiched between Asian giants India and China, votes to elect a new constituent assembly to decide the fate of the monarchy the Maoists want abolished.
One of the blasts occurred outside a school and near the newly built United World Trade Centre business complex in the Tripureswor area in the centre of Nepal's capital.
Another occurred less than a mile away in the central Sundhara area outside some shops, while the third took place in a mini-bus outside the gates of an industrial park in Balaju, a north-western suburb. No group claimed responsibility for the attacks and police had no immediate suspects.
"The two dead are women, and the number of injured now is 21," said a police officer, who did not want to be named as he is not authorised to speak to the media.
A witness at the site of one of the city centre blasts said he saw many people falling to the ground. "I was cycling to work when I heard a big explosion ... Soon I saw people falling down," said Sunil Maharjan. "I put three students who were injured in a taxi and took them to the hospital."
Padam Bahadur Magar, the driver of a city bus carrying 70 passengers in Tripureswor, said the blast took place just as he stopped the vehicle. "It was a big explosion, the windows of my bus were shattered and the bus was damaged. Some of my passengers were injured," he said.
Another witness said he saw school text books and pens scattered on the bloodstained ground. Police stepped up security in the ancient, temple-studded city and the surrounding valley areas.
The blasts shattered a long spell of peace in Kathmandu Valley, which began after the Maoists and the government reached a truce last year, ending a decade-long insurgency that killed about 13,000 people.