Groups of Hong Kong residents gathered at police stations across the city on Saturday morning, as a show of gratitude to law enforcers who have stood their posts in the face of escalating violence.

The activities are part of a city-wide campaign to support the police, initiated by Safeguard Hong Kong. The group has also launched activities including visiting police stations and posting messages of support on a Facebook page.

The supporters arrived at Central District Headquarters in groups. Some brought self-made postcards, saying "thank-you" and other wishes of support. Some brought fruit baskets and drinks, to giving officers a break from the sweltering heat.

As of 10.30 am, three-quarters-of-an-hour after the first arrivals, hundreds had gathered in front of police stations. They chanted slogans, like "Hong Kong Police are the best!" and "Your hard work is acknowledged!"

A police representative received the gifts and well best-wishes from the demonstrators.

Similar shows of support took place at the Kwun Tong and Kwai Chung police stations.

The Saturday event marked the fourth pro-police campaign since violent protests erupted in the city in the mid-June. Since then, tens of thousands of people have attended rallies in support of the hard work of law enforcement.

Earlier on the same day, an open letter appeared on the first pages of several influential local newspapers. The letter, from anonymous Hong Kong residents, calls on all of Society to support the Hong Kong police in their efforts to restore peace in the city.

"It broke my heart when I saw many of you get injured in clashes with rioters," a netizen commented under a post of Hong Kong police's social media account.

Since the protests broke out in mid-June, in opposition to a planned extradition bill, Hong Kong's law enforcers have faced escalated attacks from radical protesters. The families of some officers also came under attack.

Late Friday night, a gang of radicals gathered in front of Wong Tai Sin Disciplined Services Quarters. They were seen chanting offensive slogans and throwing joss paper – burnt offerings for the deceased.

It was the second time the police quarters had been besieged by radicals. On Aug 3, a gang of radicals attacked the Wong Tai Sin Quarters, hurling fireworks and numerous projectiles into the building. During the assault, windows of lower-floor residential units were smashed, gates to the car parks other government property were damaged.

During the past week, radicals defaced the exterior of the Tsim Sha Tsui police station with offensive graffiti. The protesters smashed parked cars on the premises. The Sham Shui Po police station also came under attack. Protestors set fire on the street outside.