Robots might be cheaper to employ than humans, but it seems they still need to work on their people skills. Last week, a robot security guard at the Stanford Shopping Center in Silicon Valley knocked down a toddler while on duty and then apparently just kept on driving. A report from local news channel ABC7 says the bot hit 16-month-old Harwin Cheng, knocking him to the floor.

Cheng was not seriously hurt by the incident, but we're still going to chalk this up as a violation of Isaac Asimov's first law of robotics: "A robot may not injure a human being or, through inaction, allow a human being to come to harm." Here's ABC7's story:

It amuses shoppers of all ages, but last Thursday, 16-month-old Harwin Cheng had a frightening collision with the robot. "The robot hit my son's head and he fell down facing down on the floor and the robot did not stop and it kept moving forward," Harwin's mom Tiffany Teng said. Harwin's parents say the robot ran over his right foot, causing it to swell, but luckily the child didn't suffer any broken bones. Harwin also got a scrape on his leg from the incident. "He was crying like crazy and he never cries. He seldom cries," Teng said.

16 mo old has injuries to leg, foot after @StanfordShop security robot knocks him down and runs him over. #paloalto pic.twitter.com/tJdDNeFJq1 — Lilian Kim (@liliankim7) July 12, 2016

The robot in question was the Knightscope K5, a five-foot, 300-pound machine that began trials in the mall last year. The robot trundles about on wheels and uses an array of sensors and cameras to monitor its environment. Human security guards can direct it to certain locations to see what's going on, and the bot is supposed to report any unusual activity to a central guard station. The robot's creators describe it as possessing a "commanding physical presence" combined with "advanced technology."

The k5 costs just $6.25 an hour to employ — less than minimum wage

It's not clear exactly what happened with Harwin Cheng, and Knightscope has yet to issue any statement on the matter or respond to requests for comment from The Verge. And while it seems the incident with Cheng was minor, Knightscope obviously wouldn't want something like this to happen again. Even though the K5 only costs $6.25 an hour to employ (that's lower than minimum wage), no-one's going to hire a robot that runs into children.

Update July 14th 03.40AM ET: Knightscope has issued a statement on the incident, describing it as a "freakish accident," and stressing that the K5 has driven more than 25,000 miles without similar occurrences. The company also said it reached out to the Chengs multiple times with no response, and has invited the family to the Knightscope headquarters so team members can "respectfully apologize in person and learn from this incident."

The company also provided a description of the event as registered by their sensors:

A K5 Autonomous Data Machine (Machine Identification Number 13) was patrolling at a local shopping center when, at approximately 2:39pm PDT, a child left the vicinity of his guardians and began running towards the machine. The machine veered to the left to avoid the child, but the child ran backwards directly into the front quarter of the machine, at which point the machine stopped and the child fell on the ground. The machine’s sensors registered no vibration alert and the machine motors did not fault as they would when encountering an obstacle. Once the guardians retrieved the child and the path was clear, the machine resumed patrolling. The entire incident lasted a few seconds and a scrape on the child’s leg and a bruise with minor swelling were reported.

"Our first thoughts are for the family and we are thankful there were no serious injuries," said Knightscope chief executive William Santana Li. "Our primary mission is to serve the public’s overall safety, and we take any circumstance that would compromise that mission very seriously."

Can we build a conscious computer?