ISLAMABAD (NYTIMES) - In black suits, white shirts and black ties, hundreds of lawyers forced their way into the Lahore cardiology hospital, smashing windows and damaging equipment.

Doctors ran for cover, and unattended, panicked patients ran for their lives. The hospital wards were littered with shards of glass and broken furniture.

Riot police used tear gas canisters, water cannons and batons to disperse the intruders. The melee at the hospital, the Punjab Institute of Cardiology, lasted for hours on Wednesday (Dec 11), shocking the country.

In the end, officials said, three patients died. And now, at least 80 lawyers have been arrested by Pakistani authorities, while Prime Minister Imran Khan has ordered an investigation.

The lawyers said they were avenging an attack in November by doctors and staff of the hospital, after the lawyers demanded preferential treatment.

Local news media reported that a lawyer visited the hospital for treatment of his relative in late November.

He ended up having an argument with the hospital staff and brought some lawyer colleagues for his support. The heated exchange turned violent, and the hospital staff and doctors injured three lawyers within the hospital building, the news reports said.

Since that time, the lawyers tried to get police cases registered under terrorism charges against the doctors and get them arrested.

Lahore police tried to mediate between both groups; no arrests were made at the lawyers' behest over the November incident.

Earlier this week, lawyers carried out a strike and staged a protest demonstration against police for failing to arrest the doctors involved in the November incident.

On Wednesday, the lawyers said they decided to protest at the cardiology hospital after they felt provoked by the doctors.

"In any society, no matter what the situation, such an attack on a hospital has never taken place," said Mr Muhammad Basharat Raja, the Punjab law minister.

Paramilitary troops have been deployed at important government buildings in Lahore, the provincial capital, to quell further unrest.

In recent years, lawyers in Pakistan have not shied from resorting to violence and taking the law into their hands. They have attacked judges over disagreements during court hearings, and clashes with police are frequent.

Pakistani lawyers in general have been emboldened since 2007, when a political opposition protest campaign against then military dictator General Pervez Musharraf was spearheaded by lawyers.

Images of lawyers - dressed in their customary black coats and black ties - clashing with police had assumed iconic status, as Gen Musharraf struggled to maintain his grip on power and was eventually ousted.

Some of the lawyers involved in Wednesday's attack said they were moved to act by a viral video by one of the doctors, who mocked and ridiculed them through reciting poetry and belittling remarks.

The lawyers livestreamed the run-up to their attack on the hospital as they walked toward the building. In one video, an unidentified lawyer is seen challenging the doctors, saying the doctors had invited their death and could not escape the wrath of the lawyers.

"Look at the sea of lawyers, doctor," the lawyer said in a bombastic tone. "Today, we will insert stents in the doctors."

Local news media reported that some lawyers carried weapons and fired in the air to spread panic. A police vehicle was set on fire during the violent stand-off.

The provincial information minister, Mr Fayaz-ul-Hasan Chohan, was also beaten up by the lawyers as he tried to mediate between the lawyers and the doctors.

"The lawyers tried to abduct me," he said.

A video of Mr Chohan went viral on social media. Lawyers could be seen punching and pulling the minister's hair as he and some journalists tried to extricate him from a group of lawyers.

On Thursday, the Pakistan Bar Council said the lawyers would observe a countrywide strike on Friday against the "biased conduct of Lahore police".

Mr Yasmin Rashid, the provincial health minister, said the government would take stern action against the lawyers. Mr Rashid said the lawyers exhibited inhuman behaviour and even manhandled a pregnant doctor during the ransacking of the hospital.

"No one could imagine that such a day would come in Pakistan, when patients had to be provided security from the lawyers," Mr Rashid said.