Sanaa, Yemen (CNN) -- Explosions rocked two government security offices Thursday morning in Aden, Yemen. The first explosion occurred at the city's political security headquarters, while the other was at al-Mualla police station, witnesses said.
No casualties were reported among security forces from either explosion, a security official at al-Mualla police station said. Explosives had been hidden behind the police station, the official said.
In all, at least four blasts were heard over the course of an hour in the city's al-Mansoora and Mualla districts.
Residents said that security forces fatally shot a child minutes after the explosions. "Police officers went on rooftops and started shooting," said Khaled Saleem, a resident of al-Mualla.
No immediate claim of responsibility was made, and speculation differed over who could have been behind the attacks.
A security official in Aden said it was unlikely that al Qaeda in the Arabian Peninsula was involved.
"The targets of the attack were security buildings but they seemed to be weakly planned," said the official.
However, a Yemeni government official who cannot be identified because he is not authorized to speak to the news media said that al Qaeda in the Arabian Peninsula elements are suspected, since the group "vowed recently to retaliate for attacks against them in Abyan Province."
Al Qaeda in the Arabian Peninsula has a presence in the southern province of Abyan, a U.S. official has said. It's also home to an Islamic militant movement that has targeted government troops.
In the capital city of Sanaa, clashes resumed early Thursday between tribes loyal to the Ahmar tribe and government forces in Hasaba district.
The clashes were in four areas of the district, one near the Interior Ministry, witnesses said.
Tribal fighters loyal to Sadeq al-Ahmar, the chief of the Hashed confederation, were seen gathering after Republican Guard forces tried to approach the residential compound of Sheikh Ahmar.
"This is what the Saleh regime has been hoping for all along," said Osair Abdul Karim, a tribal fighter who entered Sanaa a month ago, referring to President Ali Abdullah Saleh, who has been in Saudi Arabia recovering from wounds suffered in an attack in June on his palace. "They want to kill, and we will defend ourselves."
Heavy artillery was used in the clashes, he said.
Clashes between Hashed tribesmen and government forces continued for 11 days in May resulting in the deaths of more than 80 people and the wounding of more than 400 others.
Thousands of houses were damaged in the spring fighting.
Mohammed Jamjoom contributed to this story