BEIJING >> Chinese police have detained a suspect in a stabbing attack on four instructors from Iowa’s Cornell College who were teaching at a Chinese university in the northeast city of Jilin, officials said Tuesday.

Jilin city police said a 55-year-old man surnamed Cui was walking in a public park on Monday when he bumped into a foreigner. He stabbed the foreigner and three other foreigners who were with him, and also stabbed a Chinese person who approached in an attempt to intervene, police said.

A police statement did not give any indication of the motive for the attack.

The instructors from Cornell College were teaching at Beihua University, officials at the U.S. school said.

The injured were rushed to a hospital for treatment and none was in critical condition, Chinese Foreign Ministry spokesperson Lin Jian said at a daily briefing Tuesday. He said police believe the attack in Jilin city’s Beishan Park was an isolated incident, based on a preliminary assessment, and the investigation is ongoing.

Cornell College President Jonathan Brand said in a statement that the instructors were attacked while at the park with a faculty member from Beihua, which is in an outlying part of Jilin, an industrial city about 600 miles northeast of Beijing. Monday was a public holiday in China.

Nicholas Burns, the U.S. ambassador to China, posted on the social media site X that he was “angered and deeply troubled by the stabbing” of three U.S. citizens and one non-citizen resident of Iowa. “We are doing all we can do help them,” he wrote.

The attack happened as both Beijing and Washington are seeking to expand people-to-people exchanges to help bolster relations amid tensions over trade and such international issues as Taiwan, the South China Sea and the war in Ukraine.