Artillery and tanks pummeled the Syrian city of Homs for the fifth straight day today and activists told ABC News that at least 50 people were killed.

Today has been the heaviest day of shelling since the most recent assault began on Feb. 3, at least 150 people are believed to have died in the last 48 hours.

Tanks rolled into the city's Bab Amr neighborhood before dawn and a  live stream from Bab Amr shows a constant barrage of heavy shelling and gunfire. As explosions interrupted morning prayers, a rainbow appeared over the city. After several minutes of constant gunfire, the muezzin went quiet momentarily and chants of "Allah Akbar" filled the silence before the voice over the mosque's loud speaker resumed the call to prayer.

Activists say the roads into Homs are blocked, allowing no one in and no one out. Videos show tanks rolling through empty city streets, making it nearly impossible for residents to leave their homes.

Omar, a resident of Bab Amr, told the  BBC that the rocket and mortar attacks were indiscriminate. "Every house here in Baba Amr is a target," he said. "You have to be lucky to survive."

A doctor in the city told Al Arabiya that "whoever escapes death under the shelling will never escape the fire of snipers."

The BBC's Paul Wood spoke with journalists in Homs who said "they simply cannot move." Wood reports that people in Homs are "absolutely terrified of a ground assault" by the Syrian Army that they fear could come any day.

Today's violence comes as Russian Prime Minister Vladimir Putin reiterated Russia's condemnation of "violence from whichever side it comes." On Tuesday, Russian Foreign Minister Sergei Lavrov met with Syrian President Bashar al-Assad in Damascus, saying afterwards Assad is "completely committed" to ending the violence.

Also on Tuesday, Gulf Arab states announced they would recall their envoys from Damascus and expel their Syrian ambassadors. This comes after the U.S. shuttered its embassy in Syria on Monday. And the European Union said it will impose harsher sanctions on the regime.

As the international community debates its next move, activists abroad and inside Syria appeal for outside help.

Standing next to a dead child in a field hospital today, activist Danny Adbul Dayem made a desperate plea: "This child lost his brains. A bomb landed in his house. Is this what the U.N. is waiting for?"