Four suspected militants have been arrested in connection with a series of blasts targeting the firing range facility of a police training school at Koh-e-Murdar in Quetta earlier this week, Senior Police Superintendent (SSP) Ghulam Muhammad Dogar said on Friday. "We are interrogating them and are hopeful of getting some valuable information from them," the SSP said, adding that the police were also focusing on nationalists' involvement after the outlawed Baloch Liberation Army (BLA) had claimed responsibility for the blasts. BLA spokesman Meerak Baloch had telephoned newspapers offices in Quetta on Thursday to claim responsibility for the blasts and warned of more attacks. He said: "We have told all people in Balochistan to refrain from agencies and forces taking part in the military activity against them." However, a local police officer said on condition of anonymity: "We have arrested some suspects, but not the key men."