MOGADISHU, Somalia — A huge explosion from a truck bomb killed at least 20 people in Mogadishu, the police said on Saturday, and shaken residents called it the most powerful blast they have heard in years.

The explosion appeared to target a hotel on a busy road in the Hodan district and at least 15 people were injured, Capt. Mohamed Hussein said. Security forces had been trailing the truck after it raised suspicions, he said.