Indian police said on Friday they have detained hundreds of people and are keeping a heavy presence in northeast New Delhi, days after the worst bout of communal violence in the capital in decades. At least 38 people were killed in Hindu-Muslim violence this week, police said, amid mounting international criticism that authorities failed to protect minority Muslims. Media said the toll was likely to rise. Delhi police spokesman MS Randhawa said police is collecting evidence, reviewing video footage of the violence and has already detained more than 600 people. “The detentions were important to bring the situation under control,” Randhawa told reporters, adding that there had been no new reports of violence. The clashes began over a citizenship law that Prime Minister Narendra Modi’s Hindu nationalist government introduced in December providing a path to Indian citizenship for six religious groups from neighbouring countries – but not Muslims. Critics say the law is discriminatory and comes on top of other measures such as withdrawal of autonomy for Muslim-majority Jammu and Kashmir that has deepened disquiet about the future of India’s 200 million Muslims. Critics of the government however blamed this week’s violence on members of Modi’s Bharatiya Janata Party (BJP), which was trounced in local Delhi elections at the beginning of the month. The BJP has denied the allegations. The violence morphed into street battles between Hindu and Muslim groups with the police largely ineffective in ending the violence. The Organisation of Islamic Countries (OIC) has condemned the violence against Muslims and vandalism of mosques and Muslim-owned properties. US Democratic presidential hopeful Bernie Sanders accused President Donald Trump of failing on the issue of human rights after he refused to be drawn into criticising New Delhi for its handling of the violence.