Hunting group, Shanghai, ca. 1910

Cannot recognise the structure. Don't think it is Hong Kong. There are some photos of shooting and hunting parties on this website here . The vegetation and spindly trees look more like those in Shanghai.

This would be the remains of a Chinese stone gateway, derived from the Indian torana. You can see from its structure where the Chinese character for 'gate' comes from. 

moddsey is right, I don't think this is in Hong Kong or its style. If you look at the photos of John Sullivan in the link provided by moddsey, this chap's photo collection of his time in China was restricted to Shanghai and its environs, notably Soochow and Lake Tai, Hangzhou and its West Lake. He went on his numerous excursions by boat. 

The point is, if you use those photos as a proxy, you can imagine gweilos in Shanghai hiring a Chinese guide (I half wonder if it is the same guy in your photo!) for a hunting trip into the Chinese interior and getting photo souvenirs along the way, whether they manage to hunt anything or not. They actually have guns with them so if they were lucky they might bag a deer, wild boar, maybe a bird. 

So I suspect this ruined stone gate was highly likely in southern Jiangsu or northern Zhejiang province - and to be more precise, likely within walking distance of the banks of the Huangpu River (where they sailed from Shanghai towards Soochow, just like John Sullivan and Co.) for that all important 'exotic' souvenir shot where their Chinese guides would lead them. The gentlemen are well dressed, clean and with sparkling white shoes (!) so I don't think they have been traipsing through much undergrowth nor can I imagine them lugging a carcass from Hangzhou back to Shanghai.

The gateway is in ruins with not much ornamentation across its stone lintels and there is nothing much architectural behind the gate (a forest if anything) so it's likely they were actually standing within a courtyard (or path leading to something) and the actual front of the gate was facing the trees (unless that little mound behind them was a Chinese grave and that is what they wanted to illustrate with this photo)

Shanghai 1910. For those interested, the captioned title by Henling Thomas Wade can be read here: https://www.virtualshanghai.net/Asset/Source/refBibliography_ID-3144_No-01.pdf Takes time to download.