* Inmates raided prison armoury, official says
* Elite police commander in intensive care
* Army called in as violence rages into the night (Adds details, quotes)
COLOMBO, Nov 10 (Reuters) - Thirteen people were killed and a senior police officer was seriously wounded in a gunfight in Sri Lanka's biggest prison that began when police came under fire from inmates, officials and police said on Saturday.
The army was called in to help control the violence that continued overnight, and some staff at the Welikada prison in the capital Colombo were being held hostage by inmates, jail officials said.
Witnesses said they saw police shooting towards the jail, where armed prisoners were on the roof.
Prisons Commissioner P. W. Kodippili told Reuters that the prisoners had obtained the weapons - some of them machineguns - by breaking into the prison armoury.
"They have handed over four weapons but we do not know how many are in their position" of being armed, he said,
The commanding officer of the elite police force that had come under attack was in intensive care, as were two other people, the head of Colombo National hospital said.
"We've got 45 injured and 13 (of them) brought in dead," Dr. Anil Jasinghe told Reuters.
The violence erupted when officers from the Special Task Force (STF), Sri Lanka's elite police commandoes, were searching the jail for drugs and illegal mobile phones.
"When they were coming out, prisoners started to attack them with stones. The STF used teargas and the prisoners fired at the STF," Police Spokesman Prishantha Jayakody said.
The jail houses some members of the former defeated Tamil rebels from the minority Liberation Tigers of Tamil Eelam (LTTE) movement that fought a protracted war of independence, ending in 2009, but officials said it was unclear how many, if any, of them had been involved in the uprising.
"We don't know who is involved in this, I don't think any LTTE suspects are involved but I don't know," Commissioner Kodippili told Reuters.
(Reporting by Ranga Sirilal; Editing by Michael Roddy)