At least 26 people have been killed by a car bomb in southern Yemen, officials say.
The blast struck outside a presidential palace in the city of Mukalla, in Hadramawt province.
Elite republican guards were among the dead.
The attack came after Yemen's new President Abdrabbuh Mansour Hadi took the oath of office, replacing Ali Abdullah Saleh, who resigned after months of protest against his rule.
Mr Hadi was elected in a single-candidate poll on Tuesday, which was marred by violence in the south of the country. Nine people died in the clashes.
The election followed a deal brokered by Yemen's neighbours to end the crisis.
Mr Saleh will formally hand over power in a ceremony on Monday.
An unnamed military official said the vehicle which exploded was a pick-up truck driven by a suicide bomber, AFP news agency reported.
The palace is guarded by the elite troops, who are under the command of Ali Abdullah Saleh's son, Ahmed, AFP said.
A short while earlier, Mr Hadi was sworn in in the capital Sanaa, 540km (330 miles) to the west.
Yemen has been plagued by rebellion, with a separatist movement in the south and a Shia insurrection in the far north, as well as growing influence of al-Qaeda.
There have been growing fears that extremists might try to take advantage of the crisis which led to Ali Abdullah Saleh's resignation.
In a speech broadcast live on television, Mr Hadi vowed to continue the fight against al-Qaeda, calling it a "national and religious duty".
"If we don't restore security, the only outcome will be chaos," he said.
He also promised to work to bring home the thousands of internal refugees created by fighting between government troops, southern separatists, mutinous military units, and other factions.
Mr Hadi, who is from the south, has previously called for dialogue with the separatists.