The relentless shelling and bombardment of Homs,  Syria's third-largest city, was as fierce today as it has been  for the past three weeks.

Alex Renton, from the activist organization Avaaz, which has has established a network of activists and civilian journalists on the ground in Syria, told ABC News that there had been fighting ' 'on all sides of Baba Amr, " a section of Homs the Syrian military is trying to recapture, "but not yet inside." Renton described today's shelling as "unprecedented."

Syrian government tanks surround Homs as it prepares to launch a ground operation to "clean" the city within hours,  one Syrian official told the AP. Communications and power have reportedly been  cut since Tuesday.

Homs is under fire from heavy artillery, rockets and tanks, and the noose is tightening, particularly around the Homs' district of Baba Amr, where the Free Syrian Army, made up of a number of defected soldiers and other armed opponents of the Syrian regime. Outnumbered and outgunned,  it controls the area, which has come to symbolize the uprising against Syrian President Bashar Al Assad.

 An unnamed security official told AFP that  "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," which is what the Syrian government has said it's doing since the uprising began last March - fighting against  "armed gangs" and "terrorists."

One Syrian activist told the BBC that there were about 400 Free Syrian Army rebel fighters in Baba Amr  who "will fight to the end."

At least 100,000 residents are trapped in Baba Amr, where Americn journalist Marie Colvin and French photographer Remi Ochlik were killed last week in an attack on a makeshift media center. French reporters Edith Bouvier and William Daniel  remain.

On Tuesday rebels successfully smuggled The Times of London photographer Paul Conroy out of Syria and into Lebanon,  but his rescue has come at a cost. Activists say 13 Syrians involved in ferrying Conroy out  of the country died in the rescue -  three were killed  trying to get Conroy out, and 10 more were killed as they tried to bring in aid.

The regime's bloody crackdown continues a day after U.S. Secretary of State Hillary Clinton told a Senate hearing that President Assad could be considered a war criminal.  "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." 

According to the United Nations, the death toll has now reached 7,500,  a number disputed by Syrian activists, who claimed that  more than 8,000 Syrians have been killed in the violence that has spread to several pockets of the country.