Rafiq Maqbool, Associated Press
The cousin of Sayed Mustafa Kazimi, one of six lawmakers killed in Tuesday's suicide bombing, cries after seeing his relative's body at a hospital.

BAGHLANI-JADID, Afghanistan — Families of young people killed in Afghanistan's deadliest suicide bombing buried their loved ones Wednesday while witnesses said some of the victims may have been killed or wounded by security guards who opened fire after the blast.

The death toll from Tuesday's bombing rose to at least 68, most of them children or teenagers. The blast occurred as the students greeted members of parliament who were visiting a sugar factory in the country's normally peaceful north. Six lawmakers were among the dead.

U.S.-backed President Hamid Karzai and dozens of other Afghan leaders watched honor guards carry the lawmakers' coffins down a red carpet at Kabul's main airport after they were flown by helicopter from the blast site some 95 miles north of the capital.

Two Afghans were arrested in connection with the attack. Provincial police chief Gen. Abdul Rahman Sayed Khail said the two had ordered women to leave the scene of the attack before the bombing, raising suspicions.

A deputy education minister, Abdul Ghafor Ghazniwal, said students he had visited in Kabul hospitals told him that a conservative cleric had told female students to go home because they should not be out in public.

Hundreds of mourners gathered at a mosque near the blast site in the town of Baghlani-jadid before moving to a simple hilltop graveyard to bury the dead. A half dozen bodies were lined up side by side, covered with colorful carpets, as men in turbans knelt beside them in tears. One family arrived after another all morning long to bury the dead.

"My son was supposed to finish school this year, but yesterday I had to peel off his blood-soaked clothes, and today I buried him," said an elderly man who broke down in tears at one grave site. He did not give his name.

The town's schools were closed Wednesday, and reporters walking by simple mud-brick homes heard women inside screaming and crying.

A teenager looking through the local hospitals said he had not seen his younger brother since the attack and was looking for any signs that he was alive or dead.

"My brother came here yesterday and after the incident, he never returned home," said Shafiqullah, 18, who like many Afghans goes by one name. "I checked all the hospitals. I couldn't find him anywhere."

Dr. Khalil Narmgui, of the Baghlani-jadid hospital, said 62 people had been buried in Baghlan province, and the six lawmakers and possibly others had been transferred to Kabul for burial. He said 84 wounded people had been hospitalized. Khail, the provincial police chief, said 106 had been wounded in all.

Narmgui said most of those killed were teenagers or children, though he did not have an exact figure. The Ministry of Education confirmed that at least 18 students and five teachers had been killed.

Narmgui, who was at the site of the attack, said he heard gunfire from security personnel for a short time after the explosion.

"I ran into a compound, and when the gunfire stopped, I came out and saw that there were dead bodies everywhere," he said.

Five people had been treated for bullet wounds in his hospital, he said. Baghlan's governor, Halam Isakzai, said it was "possible" some victims had been killed by the gunfire.

Sayed Mohammad Bakir Hashimi, a Shiite cleric in Kabul, saw three bullets wounds — one on the chest and two on the hand — on the body of lawmaker Sayed Mustafa Kazimi, the spokesman for Afghanistan's largest opposition political group. It was not known if Kazimi died from the shrapnel or from the bullets.

Karzai declared three days of mourning as officials investigated the bombing. He called the blast a "terrorist attack," but neither Karzai nor any other official publicly named any suspects, and no group claimed responsibility.

Karzai blamed the bombing on "the enemies of peace and security," a phrase often used for the militant Taliban. Such a spectacular attack also could have been the work of al-Qaida.

The Taliban on Tuesday denied it was responsible.

The northern region where the blast occurred is known for tensions between the mainly ethnic Tajik government leadership and remnants of the militant group Hezb-i-Islami. Its fugitive leader Gulbuddin Hekmatyar, an ethnic Pashtun, has joined the Taliban and al-Qaida in fighting the Afghan government, although he denies direct links.