Soldier shot dead after opening fire on colleagues, killing three
* Gun fight alarms Tunis, scene of museum killings in March
* Gunman kills officer, wounds 15, before being shot dead
* School evacuated, mosque searched
A Tunisian soldier opened fire on colleagues at a military base in the capital Tunis, killing an officer and two others and wounding 15 more before being shot dead himself.
It was not immediately clear what had triggered the shooting at the Bouchoucha base in Tunis, but it alarmed a capital city still on edge after an attack in March by Islamist gunmen on the Bardo national museum.
Two military helicopters hovered overhead as police searched a nearby mosque and cars travelling on the main road between Bardo and the base. A local school was evacuated.
Three soldiers were killed and 15 wounded before the gunman was shot by his colleagues, state news agency TAP reported, citing medical sources. An army colonel was among the victims, a security source said.
Tunisian forces have been carrying out operations against Islamist fighters since March when two gunmen opened fire on tourists at the Bardo museum, killing 21 foreigners in the worst attack in Tunisia in more than a decade.
Since its 2011 uprising against autocrat Zine El-Abidine Ben Ali, Tunisia has been spared the worst chaos that neighbouring countries experienced after the "Arab Spring". But some Islamist hardliners have turned to violence.