TUNIS — A Tunisian policeman was killed and another wounded on Thursday when security forces clashed with Islamist militants on the outskirts of Tunis, three days before parliamentary elections, which voters hope will advance the country towards full democracy.

Police negotiators in the suburb Oued Ellil, to west of Tunis, were trying to persuade militants to give themselves up after the house they were in was surrounded following heavy exchanges of gunfire, officials said.

Heavily armed security forces used tear gas and stun grenades to try to force at least two suspected militants out of the house, in which officials said several women and children were being held.

“We’ve called on them to let the woman and children out, but they refused … they are family members,” interior ministry spokesman Mohammed Ali Aroui told reporters. “We have to move cautiously here.”

Tunisia has struggled to subdue hardline Islamists and jihadists opposed to the transition to democracy following the 2011 fall of Zine el-Abidine Ben Ali, and the military has cracked down hard on militants in the run up to the election.

Aroui said that as part of preemptive raids, security forces captured two suspected militants in Kebeli in the south of Tunisia who had ties to the group in Oued Ellil.

Earlier this month, security forces arrested a group of Islamist militants, including two women, saying they were planning attacks in the capital before the vote.

Among militant groups operating there is Ansar al Sharia, which the United States considers a terrorist organization and which blames for a 2012 attack on the U.S. embassy in Tunis.