Seven people were killed and 14 injured Thursday in a series of explosions at a munitions factory in Serbia, Interior Minister Ivica Dacic said, according to dpa. Several blasts occurred in the Prvi Partizan factory in Uzice, 200 kilometres south of Belgrade, on Thursday night. None of the injured were in a life-threatening condition, and they were all sent home, Dacic told local media. The cause of the accident, in which six women and one man were killed, is still unclear. After the explosions, fire broke out in underground tunnels of the factory but was soon put out. "The investigation on the cause of the explosion was not possible last night because of the smoke, so it began this morning," Predrag Maric, head of emergency services in the Interior Ministry, said Friday. "Interior Ministry experts will do their best to conclude the investigation as soon as possible ... The investigation will determine whether the safety procedures were followed, but this factory was one of the safest in Serbia," Maric told B92 television. The chief executive of the factory, Dobroslav Andic, said the production line had been overhauled just two weeks earlier and added that he has no idea what could have caused the explosion. Highest-ranking Serbian officials sent condolences to the families of the victims, and the town Uzice declared a three-day morning for the victims. Uzice's mayor, Jovan Markovic, called the authorities to explain the cause of the accident as soon as possible and said that "mostly young people" were killed in the accident. Prvi Partizan factory was founded in 1928 and has a long tradition of munition manufacturing. Since 1995, 17 people were killed and dozens injured in explosions in eight factories in Serbia.