SEOUL, South Korea — The U.S. military said Thursday its investigations confirmed that there was no white phosphorus leak at one of its air bases in South Korea, days after local authorities urged residents to evacuate over concerns about a suspected leak.

On July 28, the Pyeongtaek city government sent text messages advising its residents to move to safe places and avoid skin exposure, saying white phosphorus was leaked at the Osan Air Base in the city, which is just south of Seoul, the capital.

White phosphorus is a controversial chemical substance used in incendiary munitions and smoke shells. When ignited, it burns at extremely high temperatures and can set buildings ablaze and burn human flesh to the bone.

City officials said they lifted the evacuation alert later in the day after being informed that the U.S. military finished decontamination work. They said their earlier text messages were issued following consultations with the U.S. military and South Korean police and emergency offices.

The U.S. military said in a statement Thursday it has confirmed that the crystallization and residue identified during a routine munitions inspection on the day was not white phosphorus and did not contain traces of the substance.

It said that follow-up analysis concluded that the residue was non-hazardous surface corrosion resulting from environmental exposure over time. It said no injuries happened.

“We appreciate the city’s close partnership in keeping our community safe, and we thank everyone for their patience as our team worked to resolve this situation,” Col. Ryan Ley, commander of the 51st Fighter Wing, said, according to the statement.

The United States deploys about 28,500 troops in South Korea as deterrence against potential aggressions from North Korea.

The U.S. military presence, along with crimes involving U.S. service members and the U.S. role in South Korea’s tumultuous modern history, has been a source of anti-American sentiments among many in South Korea.

Earlier this week, eight South Korean students were detained for allegedly breaking into the Osan base while shouting anti-U.S. slogans.