Thirteen Coptic Christians from Egypt were kidnapped Saturday in neighboring Libya, the Associated Press and Reuters reported. A witness told the AP masked gunmen carried out the assault by knocking on doors at a residence in Sirte, which is between Tripoli and Benghazi. 

Early Saturday, 15 armed men "had a list of full names of Christians in the building," the witness, Hanna Aziz, told the Associated Press. "While checking IDs, Muslims were left aside while Christians were grabbed." Aziz described hearing screams, and said three of his relatives were among the hostages who were handcuffed and driven away, the AP reported.

The attack follows the abduction of seven Coptic Christians earlier this week, and the reported December killings of a Coptic doctor and his family. Last February, Reuters said, the bodies of seven Egyptian Christians who had been shot were discovered on an eastern Libyan beach. 

Two rival governments currently operate in Libya: one run by Islamist militants who in August seized Tripoli and the other by the internationally recognized government Prime Minister Abdullah al-Thani in eastern Libya.

Islamist extremists, who have found safe haven in Sirte, have targeted Egyptians and Christians amid the country's ongoing strife, the AP said.

Egypt's ambassador to Libya was kidnapped last year, and Egypt shuttered its embassy in Tripoli -- now complicating the idea of a "formal diplomatic mission" to rescue the Christians who were abducted, Reuters said.