Quetta, Oct 9 : At least four people were injured on Saturday night in a grenade attack on a security check post on Sariab Road in Balochistan's Quetta. Police said that two people were seriously injured and shifted to the hospital for treatment, Dawn reported. The grenade hurled by unidentified motorcyclists landed on the roadside, injuring four pedestrians, the police said. Police and FC personnel rushed to the site and shifted the injured to Civil Hospital. "We have received four injured in the trauma centre," Dr Wasim Baig said, as reported by Dawn. Security forces cordoned off the area and launched a search operation and took some suspects for interrogation. No organisation has claimed responsibility for the attack. On Sept 17, one person was killed and 13 others, including a woman, were injured when a hand grenade aimed at a security check post exploded close to an auto rickshaw on Sabzal road, a locality on the outskirts of Quetta. /IANS