Knifeman hunted after four victims stabbed in the back in north London

In Edmonton, four unprovoked stabbings occurred within 15 hours, targeting random, vulnerable individuals. The attacks left victims in critical or life-changing conditions. Police suspect mental health issues may be involved and are searching for a tall black male suspect. A man has been arrested on suspicion of GBH, but the investigation continues.

What factors do police believe may have contributed to the attacks?

What description was given for the attacker?