Stephen Paddock scouted possible attack locations in Chicago and Boston before settling on Las Vegas to launch the deadliest mass killing in US history, according to reports.

His potential targets included the Lollapalooza music festival in Chicago, where he booked two hotel rooms at a 21-story hotel with a sweeping view of Grant Park, TMZ first reported.

Paddock also had Googled Fenway Park and the Boston Center for the Arts, and also conducted online searches for large concert venues in the Boston area, sources told the Boston Globe.

An official who was not authorized to speak publicly told the paper it was unclear whether Paddock was ever in Beantown — or when he conducted the Internet searches.

An image posted online by TMZ shows a guest listed as Paddock/Stephen booking a room at The Blackstone Hotel for Aug. 1 and a second room on Aug. 3 — the day the Lollapalooza started. Both rooms had a checkout date of Aug. 6, when the festival ended.

Paddock specifically requested both rooms to have a view of Grant Park, where about 400,000 fans gathered for the event about 500 yards away.

Among the attendees was Malia Obama, 19, the eldest daughter of the former president and Michelle Obama.

A law enforcement official told the Globe that no evidence has been found that Paddock ever came to Chicago that weekend.

Massachusetts Gov. Charlie Baker and Boston police on Thursday said they were aware of the reports about Paddock’s interest in the city.

“We are aware of the media reports referencing a Boston connection to the Las Vegas mass shooting incident that occurred on Sunday, October 1, 2017,” the Boston police said in a statement.

“The Boston Regional Intelligence Center is in contact with our local and federal law enforcement partners here and in Las Vegas and continues to monitor the situation. There is currently no known threat to the Metro Boston Homeland Security Region related to this incident.”

Baker told reporters that the “investigation is being led by the folks in Las Vegas, and we are in constant conversation with the Fusion Center here in Massachusetts, which is in constant contact with them.”

Meanwhile, Chicago police spokesman Anthony Guglielmi tweeted Thursday that his department was aware of the report about The Blackstone.

In a statement, the department said it has “been in communication with our federal partners.”

“As you saw earlier this week the city conducts extensive public safety planning and training around major events, in close coordination with our law enforcement partners, to ensure public safety,” the statement read.

Authorities are also investigating whether Paddock rented several units at The Ogden, a luxury condo tower overlooking a bigger music festival, called Life is Beautiful, in downtown Las Vegas the weekend before Sunday’s slaughter, a law enforcement source told NBC News.

That event was held several miles north of the Route 91 Festival that Paddock sprayed with bullets from a 32nd-floor suite in the Mandalay Bay hotel, killing 58 people and wounding about 500.

Investigators have been scrambling to try and establish a motive for his massacre.

On Wednesday, the FBI questioned his girlfriend, 62-year-old Marilou Danley, who was out of the country during the attack. She has released a statement saying she had no advance knowledge of Paddock’s planned atrocity.