MOGADISHU, Somalia (AP) — A huge explosion from a truck bomb killed at least six people in Somalia's capital, police said Saturday, as shaken residents called it the most powerful blast they'd heard in years.

The explosion appeared to target a hotel on a busy road in Hodan district and the death toll could rise, police Capt. Mohamed Hussein said. Security forces had been trailing the truck after it raised suspicions, he said.

The blast occurred two days after the head of the U.S. Africa Command was in Mogadishu to meet with Somalia's president, and two days after the country's defense minister and army chief resigned.

The Somalia-based extremist group al-Shabab recently stepped up attacks on army bases across south and central Somalia. While there was no immediate claim of responsibility for Saturday's blast, al-Shabab often targets high-profile areas of Mogadishu with deadly bombings.

The U.S. military has stepped up drone strikes and other efforts this year against the al-Qaida-linked al-Shabab, which is also fighting the Somali military and over 20,000 African Union forces in the country.