Thousands of Pakistanis attended funerals Monday for victims of a bombing that killed 45 people in a Shiite Muslim area of Karachi, the latest in a series of devastating attacks ahead of elections. The bomb exploded in Abbas Town as worshippers came out of mosques, ripping through two apartment blocks, setting one of them on fire and trapping people beneath piles of rubble. Survivors are being housed temporarily in schools. There has been no claim of responsibility, but suspicion will likely fall on banned Sunni extremist organisation Lashkar-e-Jhangvi, which has claimed major attacks on Shiites in the city of Quetta, and on the Pakistani Taliban. Thousands of mourners, including women and children, many of them wearing black bands around their heads, beat their chests and heads and sobbed as eight coffins passed by at the start of the first funeral, an AFP reporter said. Traffic was thin as educational institutions, businesses and markets closed after the local government announced one day of mourning and Shiite groups three days of mourning for those killed in Sunday's bombing. At least 4,000 people turned out for the funerals, police officers estimated. Karachi is Pakistan's largest city and business hub, contributing 42 percent of GDP, 70 percent of income tax revenue and 62 percent of sales tax revenue. But the city is plagued by sectarian, ethnic and political violence, which last year killed more than 2,200 people and which routinely forces closures. Rights groups have strongly criticised the government for failing to stop sectarian murders and bombings and bring to justice those responsible. "Terrorists are killing us but the government is not taking any action to eliminate them," said Mohsin Ali, 29, a Shiite whose elder brother was killed. "How long will we keep losing our children, our relatives?" Survivors could be seen searching for personal items and belongings such as jewellery from the rubble of their apartments. "The government should provide us with arms to deal with terrorists if their agencies are unable to bring them to book," said Azam Khan, a Sunni Muslim, who said he had taken several of the dead to hospital. "We will vote for those who eliminate these terrorists. We are not ready to be hoodwinked by empty slogans any more." Officials said around 150 people were also wounded. Although Abbas Town is a mainly Shiite neighbourhood, officials said some Sunnis were among the dead. So far hospitals have released only 13 bodies for burial with the rest yet to be formally identified, officials said. Pakistan's parliament is due to dissolve in two weeks in preparation for elections. But rising violence against Shiites, who make up around 20 percent of the 180 million population, has raised serious questions about security. "The unfortunate reality is that things could take a turn for the worse as tensions increase ahead of the approaching general elections," newspaper The News wrote in an editorial on Monday. Last year was the deadliest on record for Shiites in Pakistan with more than 400 killed, according to Human Rights Watch. The Supreme Court ordered the authorities to come up with a strategy to protect Shiites after bomb attacks in the southwest on January 10 and February 16 killed nearly 200 people. Police on February 22 detained Lashkar-e-Jhangvi leader Malik Ishaq for 30 days under a law intended to maintain public order. He was detained briefly in 2012 for inciting sectarian hatred, having been released on bail in 2011 despite being implicated in dozens of murders. The Pakistani Taliban have also increased attacks in recent months, leading to fears they could disrupt the election scheduled to take place by mid-May. Last month the group proposed talks with Islamabad. But the government insists the militants must declare a ceasefire before coming to the negotiating table -- a condition they have rejected.