After at least 44 people were killed in Homs on Thursday, Syrian activists said they fear the city is headed toward another massacre.

Syrian government forces are believed to have slain members of a handful of families in the Jobar district. The army has been shelling Homs for a month, but the state blamed the recent deaths on rebels.

The army has started combing the area building by building and house by house. Now the troops are searching every basement and tunnel for arms and terrorists, an unnamed security official told the Agence France Presse.

The fresh wave of killings occurred a day after United Nations humanitarian chief Valerie Amos was allowed to visit the city.

I was devastated by what I saw in Baba Amr yesterday, Amos told Reuters, referring to the neighborhood most devastated by President Bashar al-Assad's assault on Homs.

The devastation there is significant, that part of Homs is completely destroyed and I am concerned to know what has happened to the people who live in that part of the city.

Activist Alex Renton, of the Avaaz democratic organization, told ABC News the shelling in Homs was unprecedented, adding the fighting was occurring on all sides of Baba Amr.

While Homs has become the symbolic capital of the Syrian conflict, the violence has extended to other parts of the country. On Thursday, at least 10 people were killed near Damascus and in the Idlib province, according to the SAPA news agency. Meanwhile, Al Arabiya reported that Assad sent more army troops to Idlib, where activists now fear a Homs-style assault.

The United Nations estimates 8,000 people have been killed since the violence began in Syria a year ago. International leaders have met at the U.N. and at the Friends of Syria conference to discuss how to diplomatically bring peace to the country, but so far all resolutions and sanctions have failed to convince Assad to stop his crackdown.

“I think that based on definitions of war criminal and crimes against humanity, there would be an argument to be made that he would fit into that category,” U.S. Secretary of State Hillary Clinton said on Wednesday.