According to Lamrani, some people trapped inside the 24-story Grenfell Tower were "banging, frantically smacking the windows trying to get out."
She added: "The look of frustration on their faces, as if to say ... 'we're burning and no one is doing anything.'"
Lamrani also recounted seeing a man on a lower floor who was "literally begging for his life" as the flames approached.
"He obviously couldn't find an escape route and he couldn't leave," she said. "We were gesturing for him ... to jump out. You know, a few broken bones and at least you have your life."
London Fire Brigade Commissioner Dany Cotton called the deadly overnight blaze an "unprecedented incident."
She added: "In my 29 years of being a firefighter, I have never, ever seen anything of this scale. This is a major fire that’s affected all floors of the 24-story structure from the second floor upwards."