COLUMBIA, Mo. (AP) — Sixteen national organizations are asking the University of Missouri to ensure the safety of Jewish students after anti-Semitic messages were found last week.

The organizations sent a letter to Chancellor R. Bowen Loftin Thursday about graffiti found at the Mark Twain Residence Hall.

Loftin responded that he takes the issue seriously and regretted that he did not respond more quickly.

The Columbia Missourian reports a swastika, Illuminati symbol and the word “heil” were found in the residence hall April 9. After they were cleaned off, a swastika and “You have been warned” were written the next day.

Loftin issued a statement April 14 calling the graffiti deplorable.

The organizations’ letter questioned why Loftin didn’t respond sooner and said more needs to be done to protect Jewish students.