US officials are "deeply concerned" by reports that Beijing police on Wednesday arrested prominent economics professor Ilham Tohti, together with at least six of his students, the State Department said on Thursday night. "The detention of Tohti, who has been outspoken in support of human rights for China's ethnic Uighur citizens, appears to be part of a disturbing pattern of arrests and detentions of public interest lawyers, Internet activists, journalists, religious leaders and others who peacefully challenge official Chinese policies and actions," said the statement from department spokeswoman Jen Psaki. "We call on Chinese authorities to immediately account for the whereabouts of Tohti and his students and guarantee Tohti and his students the protections and freedoms to which they are entitled under China's international human rights commitments, including the freedom of expression," Psaki said.