Tusk spoke during an emergency meeting with Cabinet ministers and senior security officials convened after the attacks in the central-eastern Mazowieckie province, which also includes Warsaw.
On Thursday, a 15-year-old former student attacked three people at a school in the village of Leszczydół-Nowiny, near the town of Wyszków, some 50 km northeast of Warsaw, killing a 37-year-old school employee and injuring two others.
A day earlier, a 19-year-old attacked schoolmates and teachers with a knife at a vocational school in Ostrołęka, 120 km northeast of the capital, injuring five students, two teachers and two other people.
Prosecutors said the assailant also attempted to detonate a homemade explosive device at the school.
In another incident, police in the town of Sierpc, 125 km northwest of Warsaw, foiled a planned school attack on Wednesday and detained a 17-year-old suspect, according to authorities.
Tusk expressed condolences to the family of the woman killed in Leszczydół-Nowiny, who left two children, and praised the school principal and a teacher who were injured while trying to stop the assailant.
"Today, all of Poland should hear about their heroism. The teachers did not hesitate to risk their lives to prevent an even greater tragedy," Tusk said.
He said the attacks in Ostrołęka and Leszczydół-Nowiny should serve as warnings, adding that the attacker in Leszczydół-Nowiny had been wearing a helmet with a camera, apparently intending to record the incident.
Tusk asked the interior minister and police chief to ensure that police patrols visit every school at least once a day as part of their routine duties.
Interior Minister Marcin Kierwiński later said patrols around schools would be increased and that instructions had been sent to local police commands. Officers will enter school premises after coordinating with principals, he said.
Risk of copycat attacks, viral challenges
Tusk said the increased police presence was intended in part to counter the risk of copycat attacks and what he called "radically foolish online challenges" inspired by recent incidents.
The prime minister also called for renewed work on legislation governing illegal online content, saying a bill previously backed by his government had been vetoed by President Karol Nawrocki.
Tusk said the vetoed legislation would have given the state tools to respond more quickly to online threats.
He said that under the current system, authorities may have to seek a court order before asking a platform to remove or block illegal content.
"If today this young knife attacker had streamed the crime online, we would not have been able to block that content because we were not given the legal tool to do so," Tusk said.
He said provisions most strongly challenged by Nawrocki had been removed from a subsequent government proposal, including provisions allowing the state to immediately block hate speech.
Tusk indicated that these provisions could be restored during parliamentary work.
Nawrocki vetoed a law implementing the European Union's Digital Services Act in January, saying the legislation raised concerns over freedom of speech. The bill would have given Polish regulators powers to issue orders concerning illegal online content.
The government subsequently split its proposed changes into two bills, state news agency PAP reported.
In September, Nawrocki signed legislation establishing the president of the Office of Electronic Communications as Poland's digital services coordinator, with the law due to take effect on November 6.
Tusk said authorities must be able to take action when online activity poses a threat to the public.
He called for the Internal Security Agency (ABW), police, the state-run NASK cybersecurity agency and other institutions to coordinate their online activities as quickly as possible, including monitoring, prevention and intervention when a threat appears to be escalating.
The government will also discuss training methods for students and teachers, Tusk said.
"We cannot shift responsibility for school safety onto teachers, students and parents," he said. "We must involve everyone concerned and we must start working."
Education ministry announces effort to improve school safety
Education Minister Barbara Nowacka on Thursday announced a new effort to strengthen school safety in partnership with the interior ministry.
The initiative will be modelled on an existing school safety programme developed together with the defence ministry, Nowacka said.
She said every school would hold special classes on emergency safety procedures.
The education ministry will also distribute a safety guide for children and teenagers covering various threats and ways young people can respond to them, Deputy Education Minister Paulina Piechna-Więckiewicz said.
The guide will be aimed at students in first through seventh grades of primary school and will come in two age-specific versions, she said.
The ministry also plans to train 7,500 school principals, with more than PLN 45 million (EUR 10 million) allocated for the effort, according to Piechna-Więckiewicz.
(gs)
Source: IAR/PAP, TVP Info