A grenade tossed into a crowded house killed at least 15 people and wounded 50 others in northeastern Somalia on Tuesday, an official said.

Most of those killed or wounded in the attack in the semiautonomous region of Puntland were Ethiopians believed to be on their way to find work in the Arabian Peninsula, which lies across the Gulf of Aden, said Muse Geele Yusuf, a senior official in the region.

Yusuf said police were searching for the attackers and trying to determine why the Ethiopians were targeted.

Ethiopia and Somalia have a long history of tense — and, at times, violent — relations. Ethiopian troops are currently propping up a shaky U.N.-backed government in the southern part of the country.

Puntland, unlike the south, has been relatively peaceful since Somalia's last functioning government collapsed in a 1991 revolt, leaving rival warlords to turn on each other and divide the nation among squabbling clans.

In Mogadishu, the capital, fighting is routine, and at least one person was killed and five wounded Tuesday in a three-hour gun battle between Islamic insurgents and government troops and their Ethiopian allies, said Liban Ahmed Nageye, a witness.

Meanwhile, in the central town of Belet Weyne, a judge was shot and killed by two men armed with pistols, police chief Abdi Aden Adow said. He said police were investigating the slaying.