Alexander Heit, a 22-year-old college student with good grades and a quick wit, was driving in Greeley, in the US state of Colorado, when he decided to reply to a text message on his phone.

"Sounds good my man, seeya soon, ill tw ... "

We don't know the rest. The message was interrupted by a crash. Heit died.

While the young man was distract-ed, he drifted into oncoming traffic, according to the International Business Times.

On my cycling trips around Beijing, I often think about the many tragic cases like Heit's that I've read about in my home country over the years.

I am astounded by the number of my fellow cyclists, and also scooter riders, who I see not only carrying on phone conversations but also reading text on their phones. Their heads are down, eyes transfixed by a small luminous screen, oblivious to the world they're rushing toward.

Of course, the faster you're going, the quicker a distraction can become a tragedy.

Studies show that staring at a cellphone for 3 seconds while driving at 60 kilometers an hour is as dangerous as driving blind for 50 meters, according to Xie Caifeng, a fellow at the research office of Shunyi court in Beijing, writing in a column published by China Daily last year.

Xie wrote that official statistics showed that "the use of cellphones while driving was the top reason for traffic accidents leading to death in Zhengzhou, Henan province".

It is also illegal. According to the national traffic code, it is illegal to use hand-held phones while driving, and an offender can lose points on their license and receive a fine of up to 200 yuan ($29.75), Xie wrote.

Penalties are one deter-rent, but education and social pressure also are important.

Two years ago, the Shanghai office of the media company Havas designed a campaign for the Global Road Safety Partnership using 350 smashed cell-phones that had been in the hands of people who had died while texting in China, showing their last words.

They were mounted on black slabs like gravestones as part of an installation for Road Safety Day in 2015, which was made into a film, SMS Last Words.

It showed heart-rending last exchanges like this one:

Driver: Don't worry, I'll be home quickly. Mother: OK, waiting for u!

As technology has spread across the world, the mobile phones that are a communications miracle have become the equivalent of a loaded gun when in the hands of distracted drivers, cyclists and pedestrians.

Alexander Heit died back in 2013. By now, he would be 26, possibly starting a new job or business, maybe engaged to the love of his life.

After his death, Heit's parents issued this statement: "In a split second you could ruin your future, injure or kill others, and tear a hole in the heart of everyone who loves you."

So, please, put the phone away, or stop when you use it if you must. The risks are just too great.

Contact the writer at matthewprichard@chinadaily.com.cn