(Reuters) – Pedestrians caught crossing the street while staring at their cellphones in Hawaii’s largest city will face a fine of up to $99 beginning on Wednesday as a new law comes into effect intended to prevent distracted people from blundering into traffic.

Bans on texting while driving are common but Honolulu becomes the first major U.S. city to extend the ban to pedestrians after the City Council passed the ordinance in July.

The law imposes fines on anyone caught crossing a street while “viewing” a cellphone or similar device. Emergency responders using their phones for their work are exempt.

First-time offenders will be fined between $15 and $35. Persistent violators will be fined up to $99.

As cellphones, particularly smartphones filled with distracting social media and messaging applications, have become more widespread, the number of pedestrians injured while paying too much attention to their phone has surged.

Between 2000 and 2007, fewer than 400 pedestrians were injured in the United States each year after becoming absorbed in their phones, according to a study in the Journal of Safety Studies in 2015. After 2007, which marked the launch of the iPhone and a subsequent slew of imitators, estimated 1,300 pedestrians were injured in 2012.

The National Safety Council added “distracted walking” to its annual list of injury risks in 2015, warning Americans of a growing danger.

Other places besides Honolulu are contemplating similar bans, including the town of Stamford, Connecticut.