TEXAS  — Rescue workers searched rubble early Thursday for survivors of a fertilizer plant explosion in a small Texas town that killed as many as 15 people and injured more than 160 others. The blast left the factory a smoldering ruin and leveled homes and businesses for blocks in every direction.

The explosion in downtown West, a farming community about 20 miles north of Waco, shook the ground with the strength of a small earthquake and could be heard dozens of miles away. It sent flames shooting into the night sky and rained burning embers and debris down on shocked and frightened residents.