Chinese police have detained a suspect in the stabbing attack on four instructors from Cornell College in Iowa who were teaching at a Chinese university in the northeastern city of Jilin, authorities said Tuesday.

Police in Jilin city said a 55-year-old man surnamed Cui was walking in a public park on Monday when he encountered a foreigner. He attacked the foreigner and three other foreigners with a knife and also a Chinese man who tried to intervene, police said.

The Cornell College instructor was teaching at Beihua University, officials at the American school said.

Chinese Foreign Ministry spokesman Lin Jian said at a daily briefing on Tuesday that the injured were taken to hospital for treatment and none were in serious condition. He said police believe the attack in Beishan Park in Jilin city was an isolated incident based on preliminary assessments and investigations are ongoing.

Cornell College President Jonathan Brand said in a statement that the instructors were attacked while they were in a park with a faculty member from Beihua, on the outskirts of the industrial city of Jilin, about 1,000 kilometers (600 miles) northeast of Beijing. Monday was a public holiday in China.

The State Department said in a statement that it was aware of the reports of the stabbing and was monitoring the situation. The attack comes at a time when both Beijing and Washington are seeking to expand people-to-people exchanges to help strengthen ties amid tensions over trade and international issues such as Taiwan, the South China Sea and the war in Ukraine.

An Iowa state legislator posted a statement on Instagram saying his brother, David Zabner, was injured in a stabbing attack in Jilin. Rep. Adam Zabner described his brother as a doctoral student at Tufts University who was in China as part of the Cornell-Beihua relationship.

“I spoke to David a few minutes ago, he is recovering from his injuries and feeling well,” Adam Zabner wrote, adding that his brother was grateful for the care he received at the hospital.

News of the incident was suppressed in China, where the government controls any information deemed sensitive. News media outlets did not report the incident. Some social media accounts posted foreign media reports about the attack, but a hashtag about it on a popular portal was blocked and photos and videos of the incident were quickly removed.

Cornell spokeswoman Jane Visser said in an email that the college is still gathering information about the incident.

Visser explained that the private college, located in Mount Vernon, Iowa, partners with Beihua University. When the program began in 2018, a press release from the college said that Beihua provides funding for Cornell professors to travel to China to teach a few courses in computer science, mathematics and physics over a two-week period.

According to a 2020 post on Beihua’s website, the Chinese university uses American teaching methods and resources to provide engineering students with an international perspective and English language ability.

According to the post, about a third of the program’s core courses use American textbooks and are taught by American professors. Students can apply to study at Cornell College for two years of their four-year education and receive degrees from both institutions.

Chinese President Xi Jinping has unveiled a plan to invite 50,000 young Americans to China over the next five years, though Chinese diplomats say the US State Department’s travel advisory has discouraged Americans from travelling to China.

Citing arbitrary detentions as well as exit bans that could prevent Americans from leaving the country, the State Department has issued a Level 3 travel advisory for mainland China — the second-highest alert level. It urges Americans to “reconsider travel” to China.

Some US universities have postponed their China-related programs due to travel advisories.

Foreign Ministry spokesman Lin said China has taken effective measures to protect foreigners. “We believe this isolated incident will not disrupt normal cultural and people-to-people exchanges between the two countries,” he said.