Syrian troops pummeled opposition neighborhoods in the city of Homs with heavy mortars on Wednesday after peace envoy Kofi Annan said Damascus had again promised to respect a ceasefire due to take effect in little more than 12 hours.

“Annan, this is your ceasefire,” ran the sarcastic voiceover on an activist video that showed a shopping mall engulfed in flames after it was hit in bombardment of the Juret al-Shayah quarter. Sniper fire cracked out incessantly in the background…

With all hostilities with rebels supposed to end at dawn on Thursday, activist videos posted on YouTube showed bombs crashing into the Khalidiya district of Homs.

Spouts of pulverized debris burst high into the air with each impact and plumes of dust and smoke drifted over the rooftops. The videos could not be verified and the Syrian government bars most independent media from the country.