Paul Pelosi, husband of the House speaker, Nancy Pelosi, was taken to hospital early on Friday after he was attacked at the couple’s home in California with a hammer by an assailant who was reported to have shouted “Where is Nancy, where is Nancy?”

San Francisco police said that they were called to the Pelosi house in the city on a “wellbeing check” at about 2.27am local time on Friday morning. They found an adult male confronting Paul Pelosi, and a hammer was being grasped by both men.

“The suspect pulled the hammer away from Mr Pelosi and violently assaulted him with it. Our officers immediately tackled the suspect, disarmed him, took him into custody,” said Bill Scott, chief of the San Francisco police department.

Scott named the suspect as David DePape, 42, adding that any motive was still being determined. Charges are to be brought at the San Francisco county jail, including attempted homicide, assault with a deadly weapon, elder abuse, burglary and other felonies.

It was reported by CNN that the suspect intended to tie the victim up “until Nancy got home” and that he had posted rightwing and conspiracy theories online, including content promoting the lie that Donald Trump was deprived of victory in the 2020 election because of voter fraud.

In a statement to CNN, an acquaintance of DePape’s said he appeared to be “out of touch with reality”. Two of the suspect’s relatives also told the network that DePape, who grew up in British Columbia, Canada, was estranged from his family.

In addition to multiple conspiracy posts on his Facebook account, which was reviewed by CNN and later taken down by Meta on Friday, DePape is also believed to have managed a blog to which he regularly posted screeds concerning the “ruling class”. The blog, which the San Francisco Chronicle reviewed and was later taken down, had a banner that said “Welcome to Big Brothers Censorship Hell”, along with numerous conspiracy posts about the government, media outlets and tech companies.

According to the Associated Press, the attacker had specifically targeted the Pelosi family home. Video footage of the house showed glass shattered in a side entrance, indicating where the break-in may have occurred.

A person briefed on the situation told AP that the intruder had confronted Paul Pelosi while demanding to know where his wife was. A similar chant of “Where’s Nancy?” was made by insurrectionists during the assault on the US Capitol on 6 January 2021.

The speaker was not at home at the time of the attack, but was in Washington DC with security protection that accompanies her at all times as standard.

Her husband suffered blunt force trauma to the head and body in the attack. He was being treated in hospital for bruising, severe swelling and other injuries.

In a statement, Pelosi’s spokesperson Drew Hammill said the speaker’s husband, 82, was “receiving excellent medical care and is expected to make a full recovery”.

“The speaker and her family are grateful to the first responders and medical professionals involved, and request privacy at this time,” Hammill said.

MSNBC on Friday afternoon reported that Pelosi was traveling to San Francisco to be with her husband, who was still undergoing surgery at the time. A Pelosi spokesperson wouldn’t comment on that report.

While the exact motivation for the attack was unclear on Friday morning, it raised fears about the safety of members of Congress and their families.

Concerns have been rising, particularly since the insurrection at the US Capitol on 6 January 2021, by extremist supporters of Donald Trump intent on overturning his supposed loss to Joe Biden in the presidential election, about a new era of violent threats against US lawmakers and their families and staff, and their security.

In July, members of Congress were given $10,000 each to upgrade security at their homes in the face of rising threats. Some have pushed for even more protection, pointing to people turning up at their homes and an increasing amount of threatening communications.

Joe Biden called Nancy Pelosi about the incident on Friday morning.

“The president is praying for Paul Pelosi and for Speaker Pelosi’s whole family. This morning he called Speaker Pelosi to express his support after this horrible attack. He is also very glad that a full recovery is expected,” the White House said in a statement.

Chuck Schumer, the Democratic majority leader in the US Senate, called Friday’s attack “a dastardly act”. He said he had conveyed his “deepest concern and heartfelt wishes” to Nancy Pelosi.

Top Republicans also expressed their horror at the attack. Kevin McCarthy, the minority leader in the House who is poised to take over as speaker should the Democrats lose control of the chamber in next month’s midterm elections, reached out to “check in on Paul” according to a spokesperson.

The Senate minority leader, Mitch McConnell, said he was “horrified and disgusted” by the assault.

Paul Pelosi is a businessman who runs his own real estate and venture capital investment firm, Financial Leasing Services, based in San Francisco. He met Nancy D’Alesandro when they were both students in Washington DC, and they married in 1963. They have five children and many grandchildren.

Nancy Pelosi has had two stints as speaker of the US House, between 2007 to 2011 and since January 2019. She represents California’s 12th congressional district.

The investigation into Friday’s attack is being handled jointly by the FBI, the US Capitol police (USCP) and local San Francisco officers.

The statement said that special agents with the USCP’s California field office “quickly arrived on scene”. A team of threat assessment investigators from the east coast was also sent to assist the FBI and the San Francisco police department with a joint investigation.

Nancy Pelosi had just returned to Washington this week from a security conference in Europe and is due to make a keynote speech at an advocacy event on Saturday evening with vice-president, Kamala Harris.

In addition to the rising threats on members of Congress, state and local politicians have also been confronted by increased threat levels. This week the campaign office of Katie Hobbs, Arizona’s secretary of state who is running for governor of the state in next month’s midterm elections, was broken into.

A suspect, Daniel Mota Dos Reis, has been charged with third-degree burglary.

Often at Pelosi’s side during formal events in Washington, Paul Pelosi largely remains on the west coast.

Guardian reporter Maya Yang and the Associated Press and contributed reporting