KABUL — Afghanistan observed a national day of mourning Sunday and dozens of corpses were sent to provinces across the country for burial two days after a Taliban attack on a northern Afghanistan army base left more than 140 soldiers dead.

Ministry of Defense spokesman General Daulat Waziri said Sunday that 10 attackers wearing army uniforms passed through two checkpoints at the base in two military vehicles on Friday.

He said security guards stopped them at a third gate and that’s when the attackers opened fire. Two suicide bombers ignited their explosives as part of the attack.

Although the government insists about 100 were killed or wounded, other sources put the toll at more than 140 dead.

The large military base in Balkh province houses and trains thousands of Afghan National Army troops. Officials there plan regional deployments and attacks, and US-supplied helicopters and fighter planes are launched from the base to support Afghan troops battling the Taliban.

On Friday, the base on a plain near the city of Mazar-e Sharif became the target of the deadliest single attack by Taliban insurgents since their regime in Kabul was overthrown in 2001. A spokesman for the Islamist militia claimed responsibility for the assault.

Witnesses and survivors said the assailants sprayed gunfire among mostly unarmed Afghan soldiers and officers, many of whom were either just leaving weekly prayers at the base’s mosque or eating in its canteen.

General John Nicholson, the top US commander in Afghanistan, praised Afghan commandos for bringing an ‘‘atrocity to an end.’’ Afghan President Ashraf Ghani flew to the area to console victims’ families.

A Taliban statement said four of the attackers were army defectors who had served at the base, and it called the rampage a ‘‘prelude’’ to the militants’ traditional spring offensive.

But the Taliban hardly let up its campaign this past winter, instead repeatedly attacking strategic cities and towns in scattered regions, and gradually gaining influence or control over greater portions of the country.

Associated Press