Protesters by the thousands marched through Chicago on Tuesday, stopping traffic in the downtown Loop and chanting anti-Trump slogans as they denounced immigration raids in Los Angeles, Chicago and other cities.

The Chicago clerk’s office has kept identifying application materials for more than 2,700 people who used the online CityKey system since December, documents ICE is seeking.

Ald. Andre Vasquez wants to investigate whether police violated the Welcoming City ordinance during an ICE operation last week. Chicago police officials said officers were on the scene to preserve public safety and did not violate the ordinance.