A Security guard at Shiv Sena chief Bal Thackeray’s Raigad farmhouse was killed and another seriously injured early on Sunday, in circumstances the police say are still unclear. Nothing was reported missing from the farmhouse.A security guard employed elsewhere, who claimed to be at the farmhouse when the crime took place, reported the incident. He said two armed intruders attacked the guards as they were patrolling the grounds of the farmhouse in Khalapur village. The guards ran into two unidentified intruders around 12.30 am on Sunday, according to the complaint registered by Sarad Meyete, a 26-year-old guard at a factory in Taloja.The intruders are said to have attacked the guards with swords. Security guard P.K. Singh (26), from Bihar, suffered grave injuries and died on the spot. Ingocha Singh from Manipur was seriously injured and rushed to Dhirubhai Ambani Hospital at Panvel. His condition is said to be stable.Special Inspector General of Police (Konkan Region) Satyapal Singh said, ‘‘The police suspect a fight among the guards, in which Singh was killed and the other seriously injured.’’ He said that Meyete has been detained for now, as he is making contradictory statements.Meyete and Ingocha Singh are from the same village and Meyete told the police he often visited Singh at the farmhouse. On Saturday night, the trio had a few drinks and dinner before the incident occurred. The official said Ingocha Singh’s condition was improving and his statement would soon be recorded.A case has been registered under sections 302, 307 and 34 of IPC for murder and attempt to murder at Khalapur police station. Further investigations are on.