BAGHDAD, Iraq — A suicide bomber walked into a funeral for two cousins who had died fighting insurgents and blew himself up yesterday, killing at least 50 people, according to officials. It was the latest strike in an internal war among Sunni Arabs, some of whom have aligned themselves with America and others with Al Qaeda in Iraq.

“The gangsters threatened us not to make the funeral,” Khalaf Farhan, wounded in the blast, recalled from his hospital bed. “They said if we hold the funeral they will kill more of us, from our tribe.”

The residents of Albu Mohammed village, about 90 miles north of Baghdad in Diyala province, had decided to defy them and bury the two men. The cousins had been kidnapped Tuesday.

Their mutilated bodies were found the next day, their hands and legs bound, with knife wounds in the stomach and bullets in the eyes and head.

Villagers, belonging to the Azzawi tribe, had only recently formed a paramilitary unit to defend the community of 4,000 to 4,500 people. Albu Mohammed sits in the Adhaim region along the Hamreen mountains, a stronghold of Sunni radicals.

The more than 100 mourners had already buried the two cousins and were sitting in the funeral tent when a man entered, Mr. Farhan recounted. He triggered the bomb and decimated the tent. At least 40 people were wounded in the attack, police said.

“Shrapnel hit my chest and my head. I saw legs and arms scattered on the ground and heads separated from their bodies,” Mr. Farhan said.

Jabbar Abed Rahman had been preparing food when the explosion ripped the area. The village had recently turned on those in their district backing Al Qaeda in Iraq, setting off a gangland-style war in the process.

“We had elements from Al Qaeda in our village. When we tried to stop their extremist activities … they told us, ‘You either work with us against the government or you will be killed,'” he recalled.

He vowed his tribe would take revenge. “We will now dig the graves of more than 40 of our men,” he said. “We will get our revenge from the remnants of Al Qaeda who are hiding in the Hamreen mountains.”

The identity and nationality of the attacker was not immediately clear.

Albu Mohammed’s tribal leader, Sheik Mahmood Azzawi, said the village had formed its Sunni paramilitary group a month ago with the aim of confronting the militants who robbed and killed passengers traveling the road between Baghdad and the northern city of Kirkuk. Villagers said some of the men hailed from the Adhaim area along with other sections of Diyala. They included fellow members of the Azzawi tribe as well as the Jabouri and Obeidi clans. Azzawi complained that the government was not supporting them in their fight even as they suffered huge losses.

“We decided not to be afraid from them,” Mr. Azzawi said, referring to Al Qaeda, “and their answer came with today’s atrocity that annihilated at least 50 of our best men.”

“We will continue battling the remnants of Qaeda. However, very regrettably we don’t get any governmental support,” he said.