Update at 2 p.m. — Police have released additional details about the stabbing and the suspect. Per a press release:
The Arlington County Police Department has arrested and charged a suspect following a malicious wounding investigation at Gateway Park. Wondwossen Kassu, 40, of No Fixed Address was charged with three counts of Malicious Wounding and three counts of Unlawful Wounding in the Commission of a Felony. He is being held without bond in the Arlington County Detention Facility.