Al Shabab.

...it's said he was busy chewing the khat drug

apparently the brakes failed and only realized when he was approaching the bump he hooted to warn people but i doubt people took notice as this buses are always hooting ,his only options was to negotiate the roundabout with the bus being on high speed it would have flipped over or to drive straight into the matatus that are usually parked i guess this is the point he hit pedestrians and hawkers

One of the rarely reported effects of miraa is desensitization, yaani jamaa haoni kitu chochote kikubwa ama cha kumshtua. Some users have a 'feeling' of invincibility which encourages risk-taking behavior (hence the careless overtaking & speeding). I know of users/chewers who have walked across ridges in shags in places they'd never dare venture had they otherwise been sober.

If you use Thika Road on a daily basis, you will agree with me that if something major is not done about these buses, we are going to hear of even worse accidents.

This culture where you harass everyone and break every law of the land because you are driving a bigger car (in size)than theirs, you have more money than they have, you a bigger body size (taller and / or have more muscle) You have a bigger title, you know someone powerful in government or police or you can just give out money and have your way will mess this country regardless of how economically empowered its citizens become.