Syrian officials say Damascus is not responsible for the massacre in a village that killed at least 92 people, including dozens of children.

A Foreign Ministry spokesman told reporters in Damascus Sunday that anti-government gunmen carried out Friday's attack. He says the government condemns what he called the “terrorist” attack, and is opening an investigation into the incident, with results expected within days. The spokesman also said U.N. envoy Kofi Annan will be in Syria Monday.

Syrian activists say the massacre in Houla was a coordinated assault by government forces and militiamen.

The attack is one of the deadliest incidents since an uprising against President Bashar al-Assad began 15 months ago.

Witnesses said the killing began when government forces shelled the village after Friday prayers.

A team of U.N. observers, headed by General Robert Mood, arrived in Houla Saturday to investigate the killings. Mood said the observers had counted more than 32 children under the age of 10 and over 60 adults killed.

U.N. Secretary-General Ban Ki-moon and the U.N.-Arab League envoy for Syria, Kofi Annan, condemned the violence as an “appalling and brutal crime involving indiscriminate and disproportionate use of force.”

The U.N. says more than 10,000 people have been killed in Syria since the government began its crackdown on dissent in March 2011.