An Ethiopian helicopter scouring the Somali capital for insurgents was shot down on Friday and crash-landed at Mogadishu's International Airport, reports said, according to dpa. Smoke billowed from the airport, after the helicopter was shot down by an anti-aircraft missile, Somali news agency Shabelle said. It was unclear how many people were on the helicopter and if there were any survivors. Meanwhile Canadian Somalia analyst Matt Bryden was reportedly arrested by government security forces in Mogadishu on Thursday night, but the details about his seizure were unclear. A barrage of shelling and gunfire continued in the coastal capital on Friday, a day after Ethiopian-backed government troops began an operation to clear the city of insurgents using helicopters and tanks. At least 30 people were killed on Thursday, Shabelle reported, in some of the fiercest fighting Mogadishu has seen since the transitional government seized the capital in late December. The Ethiopian operation was meant to purge the city of militants - believed to be a combination of clan members and remnants of an Islamist group that ruled most of the country for six months. Sounds of gunfire filled the air less than one week after the government and elders of the city's dominant Hawiye clan agreed to a ceasefire, which on Friday remained in tatters. The government, attempting to assert its authority over the anarchic Horn of Africa country, has said it would try to pacify the capital before an April 16 EU-backed national reconciliation conference that is set to draw some 3,000 participants.