GHOTKI, Pakistan—An express train barreled into another that had derailed in Pakistan before dawn Monday, killing at least 45 people, authorities said. More than 100 were injured, and rescuers and villagers worked throughout the day to search crumpled cars for survivors and the dead. Cries for help pierced the night as passengers climbed out of overturned or crushed rail cars, and continued to echo throughout the day at the scene in the district of Ghotki, in the southern province of Sindh. Heavy machinery arrived to cut open some cars, and more than 15 hours after the crash, rescuers were carefully removing wreckage as they looked for anyone who might remain trapped—though hopes were fading for survivors. The military deployed troops, engineers and helicopters to assist. At around 3:30 a.m., the Millat Express train derailed and the Sir Syed Express train hit it minutes later, said Usman Abdullah, a deputy commissioner …