ALGIERS – Algerian de-mining teams were scouring a gas refinery Sunday that was the scene of a bloody four-day standoff, searching for explosive traps left by militants who took dozens of foreigners hostage. The siege left at least 23 captives dead, and the American government warned that there were credible threats of more kidnapping attempts on Westerners. Algerian special forces stormed the natural gas complex in the Sahara desert Saturday to end the standoff, and the government said all 32 militants were killed. British Prime Minister David Cameron said Sunday three Britons were killed and another three are believed dead, as is a British resident. “Now of course people will ask questions about the Algerian response to these events, but I would just say that the responsibility for these deaths lies squarely with the terrorists who launched a vicious and cowardly attack,” Cameron said. The siege at Ain Amenas transfixed the world after militants linked to Al-Qaeda stormed the complex Wednesday, which contained hundreds of plant workers from all over the world, then held them hostage surrounded by the Algerian military and its attack helicopters for four tense days that were punctuated with gun battles and dramatic tales of escape. Algeria's response to the crisis was typical of its history in confronting terrorists, favoring military action over negotiation, which caused an international outcry from countries worried about their citizens. Algerian military forces twice assaulted the two areas where the hostages were being held with minimal apparent mediation — first Thursday, then Saturday. “To avoid a bloody turn of events in response to the extreme danger of the situation, the army's special forces launched an intervention with efficiency and professionalism to neutralize the terrorist groups that were first trying to flee with the hostages and then blow up the gas facilities,” Algeria's Interior Ministry said in a statement about the standoff. De-mining teams began going through the complex late Saturday and Sunday, searching for explosive traps left behind by the militants, the state news service said, citing security officials that it did not name. Sonatrach, the Algerian state oil company running the Ain Amenas site along with BP and Norway's Statoil, said the entire refinery had been mined. – Agencies