Updated

People flocked to Afghanistan's capital Thursday for funerals of lawmakers killed in the country's deadliest-ever homicide bomb attack, which killed some 68 people, most of them schoolchildren.

Six lawmakers, including Sayed Mustafa Kazimi, the chief spokesman of Afghanistan's only opposition group, were among those killed in the Tuesday blast in northern Afghanistan, though witnesses said some of the victims may have been killed or wounded by guards who opened fire after the blast.

Five of the lawmakers, including Kazimi, will be buried in Kabul, said Defense Ministry spokesman Gen. Mohammad Zahir Azimi. One of the slain lawmakers will be buried in Helmand province, he said.

The blast took a heavy toll on young students. It struck just as the lawmakers were about to visit a sugar factory in the province of Baghlan, where local schoolchildren, tribal elders and government officials had lined the streets to greet them.

Gen. Abdul Rahman Sayed Khail said that 106 people also were wounded in the blast, and that authorities were investigating whether some of the casualties were caused by the gunfire that erupted after the incident in Baghlan, some 150 kilometers (95 miles) north of the capital.

Two Afghans have been arrested in connection with the attack. The two had ordered women to leave the blast site before the bombing, raising officials' suspicions, provincial police chief Gen. Abdul Rahman Sayed Khail said.

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

Dr. Khalil Narmgui, of the Baghlani-jadid hospital, said 62 people had been buried in Baghlan province on Wednesday, and that the six lawmakers and possibly others had been transferred to Kabul for burial.

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

Gunfire erupted from security personnel for a short time after the explosion, said Narmgui, who was at the blast site.

"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 Baghlani-jadid hospital, Narmgui 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.

Karzai declared three days of mourning. He called the blast a "terrorist attack," but neither Karzai nor any other officials publicly named any suspects, and no group has claimed responsibility. The Taliban on Tuesday denied it had carried out the bombing.