At least 20 people were killed in south-western Pakistan after a huge explosion ripped through a crowded railway station, in what appears to be a suicide attack amid a surge in violence, officials said on Saturday. The bombing in Quetta, the capital city of the country’s most volatile province of Balochistan, left more than 30 people wounded. The number of dead is expected to increase with many in critical condition. Hundreds of passengers were waiting at the platform when the explosion took place in the morning. Images on social media showed the damaged platform, with its roof torn apart by t…