Law enforcement agencies

FILE - In this Feb. 6, 2017 file photo, Los Angeles Police Chief Charlie Beck speaks at a news conference in Los Angeles, Beck said Tuesday, March 21, 2017, that reports of sexual assault and domestic violence by Latino residents have dropped amid concerns that those in the country illegally could face deportation if they interact with police. He said that sexual assault reports have dropped 25 percent and domestic violence reports have fallen 10 percent among the city's Latino population since the beginning of the year. (AP Photo/Nick Ut, File)

Conservative MP Tobias Ellwood, left, stands amongst the emergency services at the scene outside the Palace of Westminster, London, Wednesday, March 22, 2017. London police say they are treating a gun and knife incident at Britain's Parliament "as a terrorist incident until we know otherwise." The Metropolitan Police says in a statement that the incident is ongoing. It is urging people to stay away from the area. Officials say a man with a knife attacked a police officer at Parliament and was shot by officers. Nearby, witnesses say a vehicle struck several people on the Westminster Bridge. (Stefan Rousseau/PA via AP).

Conservative MP Tobias Ellwood, left, stands amongst the emergency services at the scene outside the Palace of Westminster, London, Wednesday, March 22, 2017. London police say they are treating a gun and knife incident at Britain's Parliament "as a terrorist incident until we know otherwise." The Metropolitan Police says in a statement that the incident is ongoing. It is urging people to stay away from the area. Officials say a man with a knife attacked a police officer at Parliament and was shot by officers. Nearby, witnesses say a vehicle struck several people on the Westminster Bridge. (Stefan Rousseau/PA via AP).

Conservative MP Tobias Ellwood, left, stands amongst the emergency services at the scene outside the Palace of Westminster, London, Wednesday, March 22, 2017. London police say they are treating a gun and knife incident at Britain's Parliament "as a terrorist incident until we know otherwise." The Metropolitan Police says in a statement that the incident is ongoing. It is urging people to stay away from the area. Officials say a man with a knife attacked a police officer at Parliament and was shot by officers. Nearby, witnesses say a vehicle struck several people on the Westminster Bridge. (Stefan Rousseau/PA via AP).

Conservative MP Tobias Ellwood, left, stands amongst the emergency services at the scene outside the Palace of Westminster, London, Wednesday, March 22, 2017. London police say they are treating a gun and knife incident at Britain's Parliament "as a terrorist incident until we know otherwise." The Metropolitan Police says in a statement that the incident is ongoing. It is urging people to stay away from the area. Officials say a man with a knife attacked a police officer at Parliament and was shot by officers. Nearby, witnesses say a vehicle struck several people on the Westminster Bridge. (Stefan Rousseau/PA via AP).

Police secure the area close to the Houses of Parliament in London, Wednesday, March 22, 2017. The leader of Britain's House of Commons says a man has been shot by police at Parliament. David Liddington also said there were "reports of further violent incidents in the vicinity." London's police said officers had been called to a firearms incident on Westminster Bridge, near the parliament. Britain's MI5 says it is too early to say if the incident is terror-related. (AP Photo/Matt Dunham)

Emergency services transport an injured person to an ambulance, close to the Houses of Parliament in London, Wednesday, March 22, 2017. London police say they are treating a gun and knife incident at Britain's Parliament "as a terrorist incident until we know otherwise." The Metropolitan Police says in a statement that the incident is ongoing. Officials say a man with a knife attacked a police officer at Parliament and was shot by officers. Nearby, witnesses say a vehicle struck several people on the Westminster Bridge. (AP Photo/Matt Dunham)

Police secure the area on the south side of Westminster Bridge close to the Houses of Parliament in London, Wednesday, March 22, 2017. The leader of Britain's House of Commons says a man has been shot by police at Parliament. David Liddington also said there were "reports of further violent incidents in the vicinity." London's police said officers had been called to a firearms incident on Westminster Bridge, near the parliament. Britain's MI5 says it is too early to say if the incident is terror-related. (AP Photo/Matt Dunham)