A Massachusetts university professor who was shot at his home has died, campus officials say.
Nuno F Gomes Loureiro, 47, a nuclear science and engineering professor from Portugal, was shot "multiple times" on Monday and died on Tuesday morning in hospital, according to Brookline police and Massachusetts Institute of Technology (MIT) officials.
Police said officers responded to a call for gunshots at an apartment at about 8:30pm local time. Loureiro was taken by ambulance to a Boston hospital, where he died on Tuesday morning.
No one is in custody and police are treating the incident as "an active and ongoing homicide investigation", the Norfolk County District Attorney's Office said.
CBS News, the BBC's US media partner, reported that a neighbour said he heard "three loud bangs" Monday evening and thought somebody in the apartment building was kicking in a door.
Long-time resident Anne Greenwald told CBS that the professor had a young family and went to school nearby.
Loureiro majored in Physics at Instituto Superior Técnico in Lisbon in 2000 and obtained a Phd in physics at Imperial College London in 2005, according to his faculty web page.
The theoretical physicist and fusion scientist was known for his award-winning research in magnetised plasma dynamics.
Magnetised plasma dynamics is the study of the state of matter in which the motion of charged particles is influenced by the presence of an external magnetic field, according to Nature.
Loureiro joined MIT's faculty in 2016 and was named director of MIT's Plasma Science and Fusion Center in 2024.
His research addressed "complex problems lurking at the center of fusion vacuum chambers and at the edges of the universe", according to the university's obituary.
He also studied how to harness clean "fusion power" to combat climate change, CBS said.
"Our deepest sympathies are with his family, students, colleagues, and all those who are grieving," an MIT spokesperson said in a statement provided to the BBC.
The university added that "focused outreach and conversations" are taking place within the MIT community to offer care and support for those who knew the professor.
The centre's preceding director, Dennis Whyte, described Loureiro as both a brilliant scientist and a brilliant person.
"He shone a bright light as a mentor, friend, teacher, colleague and leader, and was universally admired for his articulate, compassionate manner," Mr Whyte told MIT News.
Deepto Chakrabarty, the head of MIT's department of physics, echoed those sentiments and said that Loureiro was a champion of plasma physics and that his recent research was "a particularly exciting new scientific direction".
Correction 16 December: An earlier version of this story incorrectly defined the kind of plasma that Professor Loureiro researched.