(Adds details, colour from near jail) KINSHASA, Oct 26 (Reuters) - Gunfire broke out near a prison in Congo's capital on Thursday, increasing tensions ahead of the final round of historic elections in the central African country. A Reuters reporter near Kinshasa's central prison heard bursts of gunfire in the middle of the day. Earlier this week, more than a dozen people jailed for the 2001 assassination of Congolese President Laurent Kabila vanished from the prison. The reporter could also smell tear gas but the cause of the shooting was not immediately clear and it was not known if there were casualties. Reuters reporters who arrived later saw several trucks and other vehicles carrying armed police and at least 60 troops in full combat gear racing towards the prison. But they said the shooting had died down. The reporters were ordered several hundred metres back from the jail, in a poor part of the chaotic riverside city, and could not see what was happening around the building. Democratic Republic of Congo will on Sunday hold the second round of its first elections for 40 years. The process, which has cost the international community $500 million, is intended to end years of war and chaos that have killed 4 million people. But tension has risen ahead of the vote, especially in Kinshasa, because of a series of clashes between supporters of the two run-off candidates, incumbent President Joseph Kabila -- Laurent's son -- and former warlord Jean-Pierre Bemba.
