A bomb blast has hit a shuttle train carrying Pakistani security personnel and their families in the country's south-west, officials say, in the latest major attack claimed by separatist militants.The explosion in the province of Balochistan on Sunday killed at least 24 people and injured around 70, according to three provincial government and security officials speaking to Reuters.The officials spoke on the condition of anonymity as they are not authorised to speak to the media.The attack was the latest in a series of strikes on trains, security forces and infrastructure in the mineral-rich province that borders Iran and Afghanistan.Pakistan has launched counterinsurgency operations in the province after some of the deadliest violence in years.The separatist militant group Baloch Liberation Army, or BLA, said in a statement to the media that it carried out the attack and described it as a suicide bombing The military said 21 hostages, four troops and all 33 attackers were killed.Earlier this year, Pakistani forces killed 145 militants in a 40-hour operation after coordinated attacks across Balochistan left nearly 50 people dead, provincial officials said.Reuters