A hand grenade was thrown late Sunday at a unit of security forces at a major Beirut intersection, injuring two policemen, an army soldier and two civilians, police said according to The Associated Press. The grenade was tossed off a bridge by assailants at the Barbir intersection and fell near a checkpoint for security forces in the Sunni Muslim neighborhood, a major commercial artery in the Lebanese capital. The assailants, believed to be riding a motorbike or in a car fled, and police were in pursuit. Two policemen, an army soldier stationed there and two civilians who happened to be passing by the area were slightly injured, the police said. At least one vehicle was damaged, according to police, speaking on customary condition of anonymity. The Beirut area has seen three big explosions in the last week, killing a woman and injuring nearly 30 people. The violence came as Lebanese troops were fighting Islamic militants at the Palestinian refugee camp of Nahr el-Bared in northern Lebanon. Scores of people have been killed in the week-old fighting. A grenade was also thrown late Sunday near an army checkpoint just outside the Palestinian refugee camp of Ein el-Hilweh in southern Lebanon, police said. There were no injuries.