(CNN) -- A Yemeni colonel and two soldiers were killed in clashes with Islamic militants in the southern province of Abyan Sunday, a security official said.
Two militants were also killed in the fighting, which occured in the city of Zinjibar, the Yemeni official said.
"Clashes are intensifying in the city and the government is trying to put an end to the militants' control over the city," according to the official, who asked not to be named because he was not authorized to speak to the media.
Residents in Zinjibar said they heard heavy gunfire and explosions Saturday and saw planes conducting airstrikes.
Yemen has been consumed with unrest for months as protesters demand an end to the rule of President Ali Abdullah Saleh.
In recent weeks, government troops have battled both anti-government tribal forces and Islamic militants, including al Qaeda in the Arabian Peninsula.
Also Sunday, tribal gunmen and government security forces clashed in the Yemeni city of Taiz, witnesses and medical officials said.
Witnesses said government tanks and armoured vehicles deployed inside the city in an effort to reclaim it after tribesmen took control last week. At least four tribesmen were wounded in the fighting, medics at Thawra hospital said.
Meanwhile, anti-government demonstrators rallied Sunday in the city's Freedom Square, witnesses said
A six-nation Gulf Arab alliance, the Gulf Cooperation Council, has tried to broker a government-opposition agreement that would lead to Saleh's departure, but that effort has so far been unsuccessful.