Aleppo bears the brunt in another day of carnage and defiance

At least 28 people were killed when two explosions ripped through state security buildings in Aleppo yesterday, widening Syria's conflict to a regime stronghold which has so far escaped major unrest.

One of the blasts tore through a street outside the city's Military Intelligence Directorate. Footage broadcast by state television showed rubble strewn over the road and five corpses lying under blankets to one side of the street.

According to a state TV presenter, who was filmed crying as the footage was beamed back, a number of children playing in a nearby park were killed in the attack. It was not possible to confirm the account.

The second blast hit a police headquarters in another part of the city. State media said at least 175 people were injured in the explosion.

The government blamed the blasts, the first since three similar attacks hit Damascus in December and January, killing dozens, on "terrorists". Opposition figures, however, accused the Baathist regime of staging the incidents to try to undermine the opposition.

The activists from the Local Coordinating Committees, who have been working to spread word of the uprising against the government of President Bashar al-Assad, claimed that security forces opened fire and killed seven people after the blasts.

The claim was repeated by the UK-based Syrian Observatory for Human Rights.

Yesterday's carnage in Aleppo came as the Syrian army continued to pound the besieged city of Homs with rocket and tank fire. Activists described the scenes of bloodshed and mayhem as President Assad's generals maintained their operation against rebel-held neighbourhoods in the city.

One man, who called himself Yusef, told The Independent he had been sick after visiting one of the makeshift field hospitals which doctors and volunteers are using to treat the wounded. "There was a woman there with no head," he said. "It had been blown off her shoulders. I couldn't look at her."

Another, who said his name was Basel Fouad, claimed there were still families trapped under the collapsed masonry of battered apartment blocks. "When they attack a house, they don't just hit it with one rocket. They hit the same house three or four times until it is destroyed," he said.

Activists and rights groups say many hundreds of people have been killed in Homs since the Syrian army launched its latest offensive last week.

According to Syria expert Joshua Landis, the ferocity of the Homs siege is a result of the anger being voiced among some regime supporters – many of whom are drawn from the same Alawite sect as President Assad – who feel the ruling elite's response to the anti-government uprising has been ineffective. "His supporters are saying he needs to smash the opposition," he said.