DAMASCUS, Syria (AP) -- An explosion ripped through a residential neighborhood in the northern Syrian city of Aleppo on Sunday and the state news agency said it was a "terrorist bombing."
The report by SANA gave no information on casualties in what appeared to be the second attack in two days on cities where President Bashar Assad's regime enjoys strong support. Three suicide bombings in the capital Damascus on Saturday killed 27 people. The government blamed those on the opposition, which it claims is made up of "terrorist" groups carrying out a foreign conspiracy.
No one claimed responsibility for any of the attacks.
Mohammed Saeed, an Aleppo resident, said a car bomb exploded near the Political Security Directorate in the city's central neighborhood of Suleimaniyeh. He said the neighborhood has a large Christian population. The Britain-based Syrian Observatory for Human Rights, which relies on an activist network in Syria, also said it was a car bomb. It said it had reports of dead and injured, but gave no numbers.
Saeed said the explosion went off around 1 p.m. and security forces started shooting in the air and cordoned off the area to prevent people from approaching. At that time of day, the area is usually crowded with people, especially on a Sunday, the first day of Syria's workweek, he added.
"It was a strong explosion. It shook parts of the city," Saeed said, citing nearby residents. "White smoke was billowing from the area."
Some opposition leaders accused the regime of orchestrating the attacks to tarnish the anti-government movement behind the year-old uprising against Assad.
Both cities are considered Assad strongholds and have remained relatively insulated from the unrest shaking much of the country since the start of the uprising.
Assad security forces have violently cracked down on dissent as protests have spread. Many in the opposition have taken up arms to defend their towns and neighborhoods and attack government troops, as the increasingly militarized conflict has become one of the bloodiest of the Arab Spring.
The U.N. says more then 8,000 people have been killed in a year.
There have been a string of large-scale bombings near government security buildings in Damascus and Aleppo that suggest a dangerous, wild-card element to the anti-government revolt. The regime has blamed the opposition, which denies any role or the capabilities to carry out sophisticated attacks.
After other similar attacks, U.S. officials suggested al-Qaida militants may be joining the fray.
A previously unknown Islamist group calling itself Al-Nusra Front to Protect the Levant claimed responsibility for previous attacks in a video posted online, saying it carried them out "to avenge the people of Homs." Homs is an opposition stronghold in central Syria that has been hard-hit in the government crackdown.
The last major suicide bombing in Aleppo was on Feb. 10, when twin blasts struck security compounds, killing 28 people. Damascus has seen a half dozen suicide bombings since December, most hitting intelligence and security buildings.
On Saturday, two suicide bombers detonated cars in near-simultaneous attacks on heavily guarded intelligence and security buildings, killing at least 27 people.
The explosions struck the heavily fortified air force intelligence building and the criminal security department, several miles apart, at approximately the same time, the Interior Ministry said. Much of the facade of the intelligence building appeared to have been ripped away.
State-run news agency SANA said a third blast went off near a military bus at the Palestinian refugee camp Yarmouk in Damascus, killing the two suicide bombers.