The Cleveland police department under fire over the recent fatal shooting of a 12-year-old boy has engaged in “excessive and unreasonable force” in hundreds of other cases, according to a withering report by the Justice Department that lists examples of officers firing at people who pose no threat and striking them on the head with their weapons.

The cases documented in the report include that of a semi-naked hostage victim who was twice fired at by a police sergeant as he tried to escape his captors, and a 13-year-old who was repeatedly punched in the face while handcuffed in the back of a police car.

Another incident involved a man shot with a Taser while he was was strapped to an ambulance gurney after suffering from seizures.

“Our review revealed that Cleveland police officers violate basic constitutional precepts in their use of deadly and less lethal force at a rate that is highly significant,” the report said. It found use of force by Cleveland police was at times “chaotic and dangerous”, even going so far as to suggest victims of crime and innocent bystanders should fear for their lives in the presence of police.

Cleveland police officers violate basic constitutional precepts in their use of deadly and less lethal force

The report reviewed almost 600 incidents of use of force by Cleveland division of police over three years up to 2013. It detailed incidents of Cleveland police “firing their guns at people who do not pose an immediate threat of death or serious bodily injury” and “hitting people on the head with their guns in circumstances where deadly force is not justified”.

The Justice Department said there were several incidents in which Cleveland police fired at suspects fleeing on foot or in vehicles when they who posed no danger to the officers or anyone else.

“Officers also use less lethal force that is significantly out of proportion to the resistance encountered, and officers too often escalate incidents with citizens instead of using effective and accepted tactics to de-escalate tension,” the report added.

Examples included officers punching and using pepper spray on people who have already been subdued, including after they have been handcuffed and at times “as punishment for the person’s earlier verbal or physical resistance”.

The investigation by the Justice Department’s civil rights division, which took 21 months, said the use of unreasonable force by Cleveland police could be summarised into four categories:

The unnecessary and excessive use of deadly force, including shootings and officers using their weapons to strike people’s heads.

The “unnecessary, excessive or retaliatory use of force” that was not lethal, but included Tasers, chemical spray and fists

Excessive force against persons who are mentally ill or in crisis, including in cases where the officers were called exclusively to check on welfare of an individual they subsequently attacked

The employment of “poor and dangerous tactics” that place officers in situations where avoidable force becomes inevitable.

The report also said that specially trained officers responsible for conducting unbiased reviews of officers’ use of deadly force “admitted to us that they conduct their investigations with the goal of casting the accused officer in the most positive light possible”.

Cleveland police have agreed to host an independent monitor who will oversee a set of reforms that were negotiated with the Justice Department. The department reached an agreement with Cleveland mayor Frank Jackson, who called for the federal investigation.

The inquiry was launched in March 2013 after several highly publicised police encounters, including the deaths of two unarmed suspects, Timothy Russell and his passenger Malissa Williams, fatally wounded when police officers surrounded their vehicle and fired 137 shots into a car at the end of a high-speed pursuit the previous November.

“The officers, who were firing on the car from all sides, reported believing that they were being fired at by the suspects,” the report said about the shooting of Russell and Williams, who each received 20 gunshot wounds. “It now appears that those shots were being fired by fellow officers.”

The report did not cover the death of 12-year-old Tamir Rice, which is under internal police review. Rice was shot on 22 November by officer Timothy Loehmann, after a 911 caller reported “a guy” in the park was pointing a “probably fake” gun at people.

Tamir Rice, 12, was shot in a park in Cleveland. Guardian

Surveillance video recovered after the incident showed Rice, who is black, handling a pistol-sized pellet gun. Loehmann shot the boy dead less than two seconds after his patrol car arrived at the scene. On Wednesday it was revealed that Loehmann had been judged unfit for police service by a different force two years earlier, after he broke down emotionally while handling a live gun.

Attorney general Eric Holder acknowledged the report was being released against a backdrop of concern over the shooting of Rice, which he said had led to “urgent, national questions”.

He also mentioned the deaths of 18-year-old Michael Brown in Ferguson, Missouri, and 43-year-old Eric Garner in New York, both unarmed black men killed by police.

In the space of 10 days, two separate grand juries decided not to indict the police officers involved in the deaths of Brown and Garner, sparking protests across the country. Holder said he recognised that “millions of people throughout the nation have come together – bound by grief and anguish” over the two deaths.

Holder and Barack Obama have both repeated in recent days that concerns over policing are not unique to Ferguson, New York and Cleveland, but have tapped into a well of concern in other communities across the country.

Police forces in New Orleans, Seattle, Albuquerque, Portland, Oregon, East Haven Connecticut, Puerto Rico and Warren, Ohio, are all currently undertaking reforms after similar Justice Department investigations into systematic civil rights violations. A federal investigation into the Ferguson police department is ongoing.

The Cleveland report, however, was especially damning. It put the blame not just on officers on the ground but the full raft of senior officers – who, the report said, have failed to properly train and supervise the rank-and-file. The Justice Department noted that it had cautioned Cleveland police over its use of force in both 2002 and 2005 – warnings that apparently went unheeded.

When the Justice Department visited one district police station, investigators said, they noticed a large sign hanging that identified it as a “forward operating base” – a military term used to describe outposts in war zones.

“This characterization reinforces the view held by some that [Cleveland Division of Police] is an occupying force instead of a true partner and resource in the community it serves,” the report said.

In the case involving the a hostage victim who fled from a house semi-naked last year, wearing only his boxer shorts, the report detailed how a sergeant fired twice at him. The shots missed, but the report said the sergeant’s “use of deadly force was unreasonable” and added: “It is only by fortune that he did not kill the crime victim in this incident.”

Many of the cases referred to in the report involved seemingly routine policing activity which quickly descended into civil rights abuses.

The report said the practice of striking people on the head with weapons, for example, was highly inadvisable, not least because it could allow a suspect to grab control of the weapon. It also risks inadvertently discharging the gun – something which, the report noted, has happened several times in Cleveland.

In one such case in 2012, an off-duty police officer dressed in civilian clothes observed what he believed was a drugs transaction between several suspects in two vehicles.

When the officer approached the car, one man – referred to in the report as “Eric” – came out of the vehicle. The officer drew his gun and ordered Eric to the ground, stating he was a police officer but declining to show his badge.

“A witness reported that she saw a man, later identified as the officer, holding a gun to Eric’s face while Eric asked repeatedly for the officer to show his badge and expressed disbelief that he was an officer,” the report said. “One of the occupants of the car later told police that he thought they were being robbed.”

The officer wrestled with Eric, striking his head with his gun, which discharged. “The officer reported that he did not know whether the bullet struck Eric, but that Eric was bleeding from the face as he ran away.” It remains unclear how seriously injured the victim was.

The previous year another Cleveland officer struck an unarmed man on the head with his gun after he tried to shoplift a bottle of wine and a can of beer from a supermarket.

Another Cleveland officer struck an unarmed man on the head with his gun after he tried to shoplift a bottle of wine

Another excessive response to a shoplifter involved a 13-year-old suspect whose name was given as Harold. The boy began kicking out when he was handcuffed in a police car. “In response, the 300lb, 6ft 4in officer entered the car and sat on the legs of the 150lb, 5ft 8in handcuffed boy,” the report said, adding that the child posed no threat to the officer.

“Nevertheless, the officer continued to sit on Harold and punched him in the face three to four times until he was ‘stunned/dazed’ and had a bloody nose.”