New Delhi, Aug. 26 -- At least 47 people were killed and more than 50 others kidnapped when armed men attacked a once-peaceful community near Haiti's capital earlier this week, the United Nations said Tuesday.

It is believed to be one of the largest mass kidnappings in Haiti in recent years, and one gang leader is threatening to kill the hostages if authorities kill any gang members as they try to secure the community nestled in the hills above Port-au-Prince.

Sunday's attack on Kenscoff pierced the belief that security in the troubled Caribbean country was improving.

"This is a major political and security test, for the government, for the police and for the international mission," said Romain Le Cour, head of the Haiti Observatory at...