The Editors Guild of India has expressed “serious concern” over attacks on journalists covering violent clashes in New Delhi over the country’s new citizenship law.

At least 13 people, including a police officer, have been killed as protests against the controversial law continued for a third day Tuesday.

The new law guarantees Indian citizenship to non-Muslim religious minorities escaping persecution in three neighboring countries – Pakistan, Afghanistan and Bangladesh. Activists and opposition politicians have described the legislation as divisive, discriminatory and against Muslims as well as the country's secular constitution.

The clashes, which erupted Sunday in the northeast part of the capital between pro- and anti-citizenship law protesters, took a violent turn Monday when U.S. President Donald Trump kicked off a two-day maiden trip to India.

“The Editors Guild of India expresses serious concern over the manner in which journalists assigned to cover the violence in Delhi have been targeted for physical attack. There are reports of journalists being hospitalized after such attacks,” it said in a statement.

The guild noted that “journalists being attacked is tantamount to a direct assault on press freedom and those guilty of having indulged in such violence must be brought to book.”

While urging the police “to take necessary steps to provide protection to journalists and prevent any such attack in the future,” it also requested that the Home Ministry, under which the New Delhi police function, “investigate these incidents and punish the guilty. The Home Ministry must also direct the Delhi police to take appropriate action.”

Several journalists who visited northeast New Delhi to cover the violence have said that they were beaten up by rioters in the area.

Nidhi Razdan, executive editor of Indian broadcaster NDTV, said on Twitter that two of her colleagues were beaten by a mob during the clashes.