A rocket attack on the Green Zone in Baghdad on Wednesday killed four foreign civilian contractors working for the U.S. government, the U.S. Embassy in Baghdad said Thursday.

The four contractors — one from the Philippines, one from Nepal and two from India — were killed in the third straight day of indirect-fire attacks on the Green Zone, a heavily fortified area in downtown Baghdad that houses numerous U.S. and Iraqi military and government buildings.

While attacks on the Green Zone had been relatively rare, in recent weeks insurgents apparently have stepped up their campaign. Earlier this week, Iraqi government officials said at least 10 rounds struck the area in one night, though no injuries were reported.

But, in late March, two Americans — a servicemember and a civilian — were killed in a rocket attack. And, on April 12, a suicide bomber infiltrated the Baghdad Convention Center and blew up a bomb in the cafeteria of the Iraqi parliament, killing himself and a lawmaker.

An umbrella group of militants led by al-Qaida in Iraq claimed responsibility for that attack.

According to The Associated Press, some 5,000 Filipinos work on U.S. military bases throughout Iraq, many serving as cooks or on maintenance crews. In July 2004, the Philippine government officially banned Filipinos from working in the country after a truck driver named Angelo de la Cruz was kidnapped.

The Philippine government agreed to the early withdrawal of a small contingent of troops in return for his release, which happened about eight months after de la Cruz was captured.

Despite the official ban, Filipinos who were working in Iraq before the decree have been allowed to stay. And, officials said, many Philippine workers from neighboring Middle East countries still cross into Iraq looking for work.

Sign Up for Daily Headlines

Sign-up to receive a daily email of today’s top military news stories from Stars and Stripes and top news outlets from around the world.

Sign up