Three days of mourning have begun in Nigeria for more than 150 people killed when their plane crashed in the main city of Lagos. The Boeing MD-83 ploughed into a printing works and residential buildings before bursting into flames. Rescue workers have been at the scene through the night. Everyone on board the aircraft died. There were also casualties on the ground, but it is not yet known how many people were killed. The airliner, operated by Lagos-based company Dana Air, had flown in from the capital, Abuja, when it crashed and burst into flames on Sunday. Aviation Minister Stella Oduah said that the pilot contacted the Lagos control tower to declare an emergency at 15:43 GMT, 11 nautical miles away from the airport. "A minute later, the aircraft disappeared from the air traffic control radar," Ms Oduah told reporters at a briefing at the Nigeria Civil Aviation Authority headquarters in Lagos. "Our hearts and prayers go out to the families of the passengers and the people on the ground who lost their lives in this tragedy," the minister said. Safety questions The plane came down in the Iju area, just north of the airport. Casualties on the ground may have been minimised because it was Sunday and the buildings were likely to have been empty. There have been distressing scenes as people have found out that they had relatives and friends on board; most of the passengers were Nigerian, says the BBC's Will Ross in Lagos. The Chinese embassy said six of its nationals died. In a statement, President Goodluck Jonathan said he had ordered the "fullest possible" investigation into the crash. On 11 May, a similar Dana Air plane - possibly the same one - developed a technical problem and was forced to make an emergency landing in Lagos, our correspondent says. Nigeria, like many African countries, has a poor air safety record, though some efforts have been made to improve it since a spate of airline disasters in 2005. Questions are now being asked about the general safety of aviation in Nigeria, as this is the fourth crash in the last decade in which more than 100 people were killed, our correspondent adds. The website of the Indian-owned Dana Air says it operates Boeing MD-83 planes to cities around Nigeria out of Murtala Muhammed Airport in Lagos. The airport is a major hub for West Africa and saw 2.3 million passengers pass through it in 2009, according to the most recent statistics provided by the Federal Airports Authority of Nigeria.