A standoff between police and one of the suspects in a Dallas shooting spree, which left at least five police officers dead and seven others wounded on Thursday night (Dallas time), ended after the suspect was killed when a robot delivered and detonated explosives where he was holed up, according to local law enforcement officials.

The move represents a potentially unprecedented use of robots to deliberately deliver lethal force in domestic policing, according to experts, raising questions about how local law enforcement officials are deploying the high-tech tools that increasingly fill their arsenals.

"We saw no other option but to use our bomb robot and place a device on its extension for it to detonate where the subject was," Dallas Police Chief David Brown said at a news conference on Friday morning. "Other options would have exposed our officers to grave danger."

Attempts by a hostage negotiator to persuade the suspect to surrender were unsuccessful, and he exchanged fire with the police during the standoff, Brown said. Three other suspects are in custody, according to police. A senior US law enforcement official familiar with the investigation identified the deceased suspect as Micah Xavier Johnson.

The shootings in Dallas occurred at the end of an otherwise peaceful demonstration spurred by police shootings this week that killed Philando Castile in Minnesota and Alton Sterling in Louisiana.

The Dallas Police Department did not immediately respond to inquiries about the exact robot used in the standoff.

But bomb disposal robots typically work like advanced remote-controlled vehicles, featuring camera feeds that are transmitted back to operators so that they can direct the units in potentially dangerous situations from afar.

According to N.R. Jenzen-Jones, the director of weapons research group Armament Research Services, robots of the likes used to examine explosive devices and manipulate small obstacles have been used frequently to deliver different types of explosives to help breach doors or clear obstacles. Jenzen-Jones said, however, that he had never heard of a robot delivering a payload that was meant to kill a subject, and was surprised that Dallas police had been so forthcoming about that information.

Peter Singer, a New America senior fellow who specialises in the future of security, also believes this to be the first time such a bot has been used to deliver an offensive explosive in a domestic policing action. However, similar tactics have been used in war zones, he said.

In his book "Wired for War," Singer noted incidents when US troops in Iraq jury-rigged primitive remote-controlled robots to deliver antipersonnel mines into alleys where they believed insurgents were hiding.

Those situations were ad hoc uses, Singer told The Post, not an established policy per se. But he noted reliance on robotics is on the rise in the military and by local law enforcement.

"The military has over 12,000 robotic systems today — and police all over the place use robots for bomb disposal and surveillance," he said.

The way the robot was used in the Dallas case is likely legally no different from sending an officer in to shoot a hostile suspect, according to University of Washington law professor Ryan Calo.

Still, the Dallas Police Department's decision to use the unit in this way could have a major effect on how the public views the increasing integration of robots into daily life, he said.

"Obviously, if one of the ways we start regularly using robots is to kill people, their deployment will cause people to have a severe, potentially fearful, reaction," he explained.

However, Calo doesn't think that this instance signals a descent down a slippery slope to a dystopian robotic police state.

"I don't expect police to use robots like this except in extreme situations as happened in Dallas," he said.

Washington Post