London (CNN) -- Sporadic looting was seen Sunday night in North London's Enfield neighborhood, but nothing like the violence that rocked the Tottenham enclave on Saturday.

London Metropolitan Police stepped up patrols Sunday night across the British capital and security personnel were on high alert.

"We do have extra resources out tonight on duty across the capital," Cmdr. Christine Jones said. "We are carefully monitoring any intelligence and ensuring we have our resources in the right places. No one wants to see a repeat of the scenes that we witnessed last night in Tottenham."

At about 6:30 p.m., police were called to Enfield, north of Tottenham, where some young people were smashing windows at two shops. A police car was also damaged, officials said. Another shop in the area was damaged two hours later.

Police appeared to be playing a game of cat-and-mouse with gangs of youth Sunday, according to CNN's Atika Shubert. Packs of young men could be seen walking the streets with hoodies on and scarves covering their faces. There were scattered reports of looted shops and smashed-in storefronts, but the level of violence seen Saturday was not repeated.

"It seems gangs are exploiting the opportunity to loot shops," Shubert said.

Fifty-five people have been arrested, Metropolitan Police said Sunday. "We believe that 51 arrests were made in connection with the disorder last night, and four have been made for offenses committed today," police said in a statement.

On Saturday, a vigil for a man killed by police turned violent. Rioters tossed petrol bombs and "missiles" at officers and looted stores, police said.

Authorities have launched a "major investigation team" to probe the incident, police said. It was given the code name "Operation Withern."

Most of the arrests were for burglary; other offenses included violent disorder, robbery, theft and handling stolen goods, the statement added.

At least 26 officers were injured Saturday night, police said.

The violence came amid protests over the killing of Mark Duggan, who was riding in a cab when he was killed Thursday. Police stopped the cab in an attempted arrest, and soon shots were fired, the Independent Police Complaints Commission said.

The commission did not say who shot the 29-year-old, nor why the cab was stopped.

IPCC Commissioner Rachel Cerfontyne said in a statement Sunday that a number of pieces of evidence taken from the scene, including a nonpolice firearm, will undergo forensic testing. Cerfontyne said that while the shooting is still under investigation, "speculation that Mark Duggan was 'assassinated' in an execution-style involving a number of shots to the head are categorically untrue."

Cmdr. Adrian Hanstock called Duggan's death "extremely regrettable."

"It is absolutely tragic that someone has died, but that does not give a criminal minority the right to destroy businesses" and "steal from their local community," he said.

Demonstrators Saturday night burned police cars, a bus and buildings to protest Duggan's death. They pelted officers with bottles and bricks as police in riot gear charged at the crowd and blocked off streets.

A double-decker bus and some buildings were also set ablaze, sending bright orange flames shooting into the night sky.

"The rioting in Tottenham last night was utterly unacceptable," a statement from the prime minister's office said Sunday. "There is no justification for the aggression the police and the public faced, or for the damage to property."

The protests started peacefully Saturday night when about 30 friends and relatives of the victim gathered outside Tottenham police station to protest the fatal shooting.

Hanstock said, "There was no indication that the protest would deteriorate into the levels of criminal and violent disorder that we saw. We believe that certain elements, who were not involved with the vigil, took the opportunity to commit disorder and physically attack police officers, verbally abuse fire brigade personnel and destroy vehicles and buildings."

Police have "recovered excellent" surveillance video of the incident, and "those who committed disorder and criminal acts will be identified" and held accountable, he said.

The Independent Police Complaints Commission has appealed to witnesses to come forward.

The investigative team announced Sunday by police will include detectives from the Homicide and Serious Crime Command, specialist investigators and police sports staff.

"Forensic examiners will slowly and painstakingly work their way through this crime scene seeking to retrieve as much evidence as possible," Metropolitan Police said in a statement.

"Anyone who has any information about those responsible for these offences that rocked the heart of the local community please get in touch with us," the statement added.

David Lammy, member of Parliament for Tottenham, called on residents to avoid any further riots. "We already have one grieving family in our community and further violence will not heal that pain," he said.

"The Tottenham community and Mark Duggan's family and friends need to understand what happened on Thursday evening when Mark lost his life," he added. "To understand those facts, we must have calm."

CNN's Erin McLaughlin, Bharati Naik and Aliza Kassim contributed to this report.