'Horrifying' Ibrahim Sharif, of Bahrain's secular Waad party, told the BBC that the police had moved into Pearl Square at about 0300 (2400 GMT) as individuals were sleeping.
Continue studying the primary story At the scene
I am at the Salmaniya hospital. We have just confirmed with the hospital authorities that far more than 300 folks were admitted and dealt with for injuries. Specifics of some of the accidents are fairly horrific - one guy appears to have been shot at very close array in the again of the head.
A range of people are reporting that not just tear gas and rubber bullets but also that dwell rounds have been used at some point. We have just spoken to a medical professional - he was at the protest site last night as a volunteer to aid individuals with simple healthcare demands. He was attacked and is in intensive care with extreme accidents. He gave us graphic specifics of how he was overwhelmed and cursed and how he feared for his life.
There is a mood of defiance between protesters below but they are in shock at what has happened. Last evening there had been a pageant environment in the square and no person noticed this coming. It will just take days to work out whether or not there is a political response, a avenue reaction, that they can appear to.
"Throughout the day there were rumours that we would have another 24 hours, but the assault has appear with no warning," he mentioned.
Mr Sharif said that he had witnessed at the very least 100 riot police on one side of the sq. and hundreds of people jogging absent down side roadways.
One protester, Mohamed, instructed the BBC the assault had been "horrifying".
"They must have employed drinking water hoses at first instead of utilizing rubber bullets and other prohibited weapons. There ended up women and children who had been terrified by the assault."
On Thursday early morning there have been angry scenes external Manama's primary hospital, Salmaniya, as hundreds of people gathered, some answering phone calls to donate blood and other individuals defacing pictures of the Bahraini royal loved ones.
One Bahrain resident, known only as Ali, who went to donate blood, informed the BBC: "Tons of people are standing at the gates of the hospital. The police have closed the area so that no individuals can get in or out - some attempted to get out and were shot at by police.
"There are several tanks, and helicopters hovering around ( via bbc.co.uk ).