One source, who did not wish to be named, got caught up in the protests on his way to a restaurant in Taksim Square.
He saw riot police on the streets but thought it was a precaution because it was a Saturday night.
He continues: "After only a few more minutes of walking we heard some yelling and saw people running. All of a sudden we were coughing and our eyes watered, so we took off in the other direction."
A block or two further on, he came across this scene.
View this video on YouTube
He says: "A giant gun-looking device (apparently a water canon) rose out of the top of the police vehicle and everyone started running like crazy."
There were also flames in a side-street.
View this video on YouTube
He then retreated to the upper level of a restaurant where he saw protesters fleeing.
View this video on YouTube
They were being forced back by riot police and tear gas.
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More images have been posted on social media.
Protests against the internet censorship laws in İstanbul #istanbul #18January
RT @Mert__Cakir: Nevizade'ye biber gazı attı ibneler
Under the law:
- Web hosts would be obliged to store all information detailing users' online activities for up to two years.
- They would have to provide this information to officials in Ankara upon request.
- Officials could order access providers to block online content deemed illegal or to be "violating privacy" of a person, without a court decision.
Turkish courts have previously blocked access to websites, including YouTube and, more recently, Vimeo.