Rescue teams are searching for dozens of people trapped in rubble after a 5.6-magnitude earthquake struck eastern Turkey, killing at least seven people. Twenty-five buildings have collapsed, including a six-storey hotel in the city of Van, where journalists and aid workers were staying, officials said. Emergency workers said 23 people had been rescued alive but that up to 100 more remained unaccounted for. Last month, a 7.2-magnitude quake in the same area killed 600 people. There have been hundreds of aftershocks since that disaster and thousands of people are still camping out in tents in freezing conditions in the area. All but three of the buildings which toppled in Wednesday's quake were empty, Turkey's deputy prime minister said, as they had been evacuated following the 23 October tremor. Besir Atalay said that the rescue work was concentrating on those structures - two collapsed hotels and one apartment building. 'Weakened buildings' The quake hit late on Wednesday at 21:23 (19:23 GMT) with its epicentre in the Edremit district, 16km (10 miles) south of Van, the US Geological Survey said. Television pictures from Van showed residents and rescuers trying to lift debris to free people trapped under ruined buildings. Rescue workers were using high-powered lights to work through the night. Mr Atalay said rescue teams were being sent to the region from the capital, Ankara, and other areas. He said the quake toppled a school and a number of mudbrick homes, as well as two hotels. A member of the Turkish parliament, Nazmir Gur, told the BBC that people in the area were getting more desperate by the hour. "The current situation is getting worse as people need tents," he said. "As we heard from the governor and from the crisis centre unfortunately there are only very few thousands of tents. As we took a tour of a neighbourhood this morning everyone was asking for a small tent to save their children and women." The BBC's Jonathan Head in Turkey says the city became the headquarters of the relief effort for the last quake, and has been flooded by aid workers and journalists. Our correspondent says some of the weakened buildings are now thought to have been brought down in the latest tremor. Some of the journalists trapped in the collapsed Bayram Hotel - a city landmark - had sent text messages to colleagues asking to be rescued, the Associated Press quoted a Turkish cameraman as saying. Rescue workers pulled a Japanese woman to safety from the ruins of the hotel almost six hours after the quake struck. Turkey's Dogan news agency said two of its reporters were missing. Alper Kucuk from the Turkish Red Crescent told the BBC they were sending two more planeloads of relief supplies to the area, including tents and blankets, as well as rescue personnel. Turkey is particularly vulnerable to earthquakes because it sits on major geological fault lines. Two earthquakes in 1999 with a magnitude of more than 7 killed almost 20,000 people in densely populated parts of the north-west of the country.