One person was injured and a vehicle was completely destroyed in a hand grenade attack at PML-N office here in Karachi on Sunday. According to police, two persons riding on a motorcycle threw a hand grenade at the PML-N office in Sherpao colony. As a resolution of the explosion, a Taxi driver near the spot was seriously injured a vehicle of PML-M worker Jalal Khan, parked in front of the office was completely destroyed. Talking to media after the blast PML-N spokesman Qadir Mandokhel said that Jalal Khan had been receiving threatening telephone calls for the last five days. He said the callers were demanding five crore rupees from him and threatening of dire consequences in case of failure to make payment. The spokesman said the bomb blast was the work of extortion mafia in the city.