MUMBAI: At least 21 people were killed and nearly 150 injured by a series of blasts in busy localities of Mumbai on Wednesday evening.

While officially India has not blamed any terrorist outfit for the attacks, Mumbai police suspect the Indian Mujahideen - a banned domestic organisation accused of carrying out several other blasts in Indian cities over the past three years - to be behind the latest attacks on the country’s commercial hub.

Arup Patnaik, Mumbai’s police commissioner, said the terrorists had used improvised explosive devices to trigger off the blasts.

The first blast occurred in Zaveri Bazaar, the heart of Mumbai’s jewellery trade, at 6.50pm, followed soon after by one at Dadar, about 10km to the north. This was followed by a third explosion at Opera House, also in south Mumbai, about 10 minutes later. All three are congested areas, with tens of thousands of traders, office-goers and commuters leaving for home.

Zaveri Bazaar has been targeted on two previous occasions -- in March 1993, when it was one of the seven locations selected by terrorists who masterminded serial blasts; and in August 2003, when twin explosions (the other at the historic Gateway of India) resulted in the death of 55 people. Wednesday’s blast shattered the calm of the past two and a half years in the city, following the 26/11 terror attacks on Mumbai.

It was the eighth incident of bomb blasts in Mumbai since 2002. The government blamed the Indian Mujahideen, which was set up by members of another banned outfit, the Students Islamic Movement of India, for these attacks.

Indian Home Minister P. Chidambaram confirmed that Wednesday’s attack in Mumbai was “a coordinated attack by terrorists”, though he refused to blame any outfit for the blasts. The minister said that investigators from federal agencies in Delhi and forensic experts from other parts of India had been flown into Mumbai to help local police.

Maharashtra Chief Minister Prithviraj Chavan, who also confirmed they were “premeditated terror attacks and cold-blooded murder of innocent people”, said the state government would work closely with the federal government in investigating the attack.

Intelligence agencies have been issuing alerts to the Mumbai police for quite some time, though police officers here claim that there had been no specific alert relating to Wednesday’s attacks.

After the blasts, a red alert was issued in Mumbai, even as the police blocked roads and exits to the city.

AP adds: Blood-covered bodies lay on Mumbai streets and people hugged and wept. Others carried the wounded to taxis. Crowds gathered in the blast areas as police questioned witnesses and bomb squads inspected the undercarriages of vehicles searching for clues and other explosives.

Motorcycles were charred, shop-fronts shattered and a bus stop ripped apart. Bleeding victims crowded into the back of a cargo truck to be taken to a hospital.

Prime Minister Manmohan Singh condemned the blasts and appealed to the people of Mumbai “to remain calm and show a united face”.

A US official said there were no claims of responsibility, or firm indication yet of which terrorist group might be behind the attack. The official spoke on condition of anonymity to discuss matters of intelligence.

At the site of the first bombing, Zaveri Bazaar, a witness described two motorcycles exploding in flames and saw at least six bodies. “People were shouting ‘Help me, help me’,” he told Headlines Today television.

Another witness showed cellphone video of several bodies sprawled across the street to the NDTV news station.

Chief Minister Prithviraj Chavan said the blasts killed 21 people and wounded 113 others.

Some media incorrectly reported the blasts happened on the birthday of Ajmal Kasab, the only surviving gunmen from the 2008 Mumbai attacks. Kasab, who was sentenced to death in Mumbai, was born on Sept 13.