A series of attacks at Yemen's defence ministry have left at least 52 dead and some 162 hurt, officials say.
A suicide car bomb blew up at the gates of the complex in Sanaa's Bab al-Yaman district, at the entrance to the old city, and a gunbattle followed at a hospital inside.
Seven foreign medical staff - doctors and nurses - are among the dead.
Yemeni security forces are fighting regional rebels and al-Qaeda, while combating lawlessness and army splits.
Defence Minister Mohammed Nasser is currently on a visit to Washington.
No group has said it carried out Thursday's attack.
Correspondents say it bears the hallmarks of al-Qaeda in the Arabian Peninsula (AQAP).
However, one government minister has blamed people linked to former President Ali Abdullah Saleh.
The dead include two German and two Vietnamese doctors, two nurses from the Philippines and one from India, according to the country's security commission.
Officials said the situation was under control and most of the gunmen had been killed.
"The attack took place shortly after working hours started at the ministry when a suicide bomber drove a car into the gate," a ministry source said, quoted by Reuters.
The blast was heard hundreds of metres away.
"The explosion was very violent, the whole place shook because of it and plumes of smoke rose from the building," an eyewitness told the agency.
Officials said a second car followed whose occupants opened fire at the complex, and a battle ensued involving gunmen in military uniforms.
The gunmen occupied a hospital at the complex, they added, but security forces later regained control of the building, which was badly damaged.
"The assailants took advantage of some construction work that is taking place to carry out this criminal act," the defence ministry said.
They were said to be armed with assault rifles, hand grenades and rocket-propelled grenades.
"Most" of the gunmen were killed, officials said, but it was not clear how many were involved.
The incident comes aid tight security in the last few weeks following a series of hit-and-run attacks on officials by militants on motorbikes, blamed on AQAP.
There were a large number of checkpoints and armoured vehicles on the streets even before the attacks, our correspondent says.
The country has been going through a painful transition since Mr Saleh was forced from office in 2011.
Presidential elections are due to be held in February 2014.