Four persons were killed and 14 others injured on Monday in a powerful car bomb explosion triggered by suspected ULFA militants at Maligaon in Guwahati. Four persons died on the spot when the bomb planted in a car at a parking area near Maligaon Chariali went off at about 2 pm, official sources said. Nine of the injured were admitted to nearby Sanjivani Hospital, two in the adjacent Northast Frontier Railway Headquarters hospital and the rest were sent to Gauhati Medical College and Hospital, sources said.