LONDON — Katherine McKenna, a paramedic, is one of a growing number of victims of robberies and acid attacks in Britain in which the perpetrators use mopeds.

The 32-year-old's phone was snatched when a scooter mounted a busy sidewalk on a street in central London late last month. She was about to respond to a call to help an elderly man who fell down some stairs.

“I was really shocked. I could not believe that it happened and I was angry," McKenna, who works for the London Ambulance Service, said Friday.

The organization was appealing for witnesses at a time when moped-riding gangs are being blamed for helping to fuel the biggest rise in crime in England and Wales in a decade. Recent figures from Britain’s Office for National Statistics show police recorded nearly 5 million crimes in the year ending March 2017 — an annual rise of 10%.

The report said 41% of robberies reported to police occurred in London.

“Sadly this type of attack is common. They are hurting people; they are putting other people in danger on the roads and pavements but they are also a danger to themselves," McKenna said. She said she has treated many people who have been seriously injured by moped-riding thieves. Often, they also injure themselves.

The three thieves on two mopeds who targeted McKenna wore helmets that concealed their identities. They remain at large.

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Last month, hundreds of delivery riders on mopeds protested outside the U.K.’s Parliament after five acid attacks within a three-mile radius in London in just 90 minutes.

Two of the victims worked for the food delivery firms UberEATS and Deliveroo and were seriously injured. Another victim sustained life-changing injuries.

Jabed Hussain, one of the delivery drivers, was attacked with acid before his moped was stolen. He said many drivers were now refusing to work after 8 p.m. and others were looking to leave their jobs out of fear of more attacks.

A 16-year-old boy has been charged in connection with the attacks. A 15-year-old boy was arrested and has been released on bail.

Figures from the National Police Chiefs’ Council show there were more than 400 attacks with acid or corrosive substances in England and Wales in the six months leading to April 2017. Bleach, ammonia and acid were the most common substances.

Metropolitan Police figures from earlier this year showed attacks involving corrosive fluids in London jumped 74% from 261 in 2015 to 454 in 2016. Across Britain, such attacks increased 30% between 2012 and 2015, according to the Times of London.

The rise in acid attacks has been blamed on gangs using the liquids as a weapon following a police crackdown on knives and guns. British law was not specific about banning acid as a weapon, but authorities have now moved to change that.

The Crown Prosecution Service announced Friday that people caught with acid or a corrosive substance can be charged with possession of an offensive weapon if they are found to be intending harm. Attackers who throw acid at someone can be sentenced to life imprisonment, even if the target is not harmed.

It came after a petition urging the government to do more to stop the attacks was signed by nearly half a million people. The petition calls for a requirement for a license to purchase acids and corrosive substances.

Since 2015, the government has required vendors to report suspicious transactions involving sulfuric acid to police because it can be used to manufacture explosives, but other acids can be freely bought.

“Acid attacks are horrific crimes which have a devastating effect on victims, both physically and emotionally,” Amber Rudd, Britain’s interior minister, said in a statement last month.

“It is vital that we do everything we can to prevent these sickening attacks happening in the first place.”