Such eyewitness observation is completely consistant with first stage impeller disintegration and shroud penetration.
THere is zero likelihood of ANY A/C taking off with visible problem, but such impeller problems are microscopic until catastrophic failure. Also, planes crash somewhere in world every day.....
One of the first steps will be to look at the maintenance records of that engine-- when was the last time is was dye tested and X-rayed. How many hours til or since overhaul? Who did the work? Genuine factory parts or Turkish knock-offs (a-la Value Jet). Facts needed here.