In 1969, Malaysia was a young nation facing a communist insurgency and fragile race relations.
The Japanese occupation and British rule fostered communal distrust and saw several smaller ethnic clashes.
In weeks before polling day on May 10, two party workers were killed in Penang and federal capital Kuala Lumpur. One was from Umno, another from the communist-linked Labour Party.
A funeral procession involving thousands was held for the Labour Party worker in KL on eve of polling. Tensions were high.
Early results showed the Alliance lost much ground to Chinese-dominated opposition parties DAP and Gerakan. In Selangor - where KL was located - the assembly was hung.
On May 11 and 12, opposition parties paraded in KL and hurled racist jibes against Malays. Outraged, Umno Youth decided to hold a counter-procession on May 13 at dusk.
The illustration below shows what happened that day:
(Locations are an approximate based on the current map.)
Rumours circulate that the Umno rally scheduled for 7.30pm might lead to trouble. Weapons are distributed among secret society members.
An unarmed Malay group traveling from Gombak to Selangor MB Harun Idris's house clash with the Chinese bystanders taunting them. Most retreat, but some on scooters continue the trip.
Malay youths have been gathering here for two hours. By now, some 5,000 are present but they are still orderly. They carry sticks and banners, but a few have parangs and keris.
Some Malays who were in the earlier clash arrive on scooters and decry "Setapak dah kena langgar".
The mob retaliates by killing a Chinese boy delivering coffee. (Read more)
Ahmad tells Harun; both try to calm the crowd. Harun climbs onto a bus to address the crowd but to no avail.
Tan Choong Cheng (left) and Abdul Rahman Mohd Noor (right) witnessed rioters attacking unsuspecting bystanders in the Kampung Baru area. Rahman was 21, Tan only 17.
By 7pm, the moving mob starts attacking Chinese bystanders. Chinese shopkeepers throw bottles at the mob, prompting retaliation and the razing of shophouses.
FRU stops mob of 150 at the Chow Kit roundabout; teargas fired. The mob retreats to Kg Baru.
FRU is stationed around the city centre - Jalan Tuanku Abdul Rahman, Jalan Raja Laut, Jalan Chow Kit, and Kg Baru.
Mobs swarm Jalan TAR and torch shophouses. Chinese and Indian shopkeepers form a defensive line.
(They used) whatever they could find - parang, poles, iron bars and bottles. I watched one old man pathetically grasp a shovel.
By 7.15pm, they blocked the four-lane Federal Highway with logs, massacred Chinese (and some Indians), then burned their cars. Violence was spreading like wildfire.
In Kg Datuk Keramat, a Chinese home is torched; an old man dies in the flames.
Chinese and Indians attack Malay-owned businesses and vehicles, after a Malay mob moves on. They try to burn down the Umno HQ but fail. Propaganda trucks are torched.
Armed Chinese men enter cinemas and attack Malay moviegoers. Many die. Near Capitol Theatre, the FRU disperse a Chinese mob of about 1,000 and rushed the injured to hospital.
Capitol Theatre was one of several theatres along Jalan Tunku Abdul Rahman attacked.
Casualties arriving at GH from now onwards are nearly all Chinese and almost all have gunshot wounds. Many were shot at close range.
There are reports of a hail of gunfire at hotspots along the Klang River and Sungai Bunus - shooters unknown. (Read more)
Bodies are piled up three-deep in the morgue. There is no more space, but bodies continue to turn up.
The General Hospital (in the background) is located about 1km from the riot hotspots.
Cars damaged during the riot on Jalan Bangsar, Kuala Lumpur
Overturned vehicle on fire at Jalan Raja Muda, where the riot started.
Gutted shophouses on Jalan Campbell
Tensions would persist for months. Chinese traders would boycott Malay farm produce. In June, fighting broke out in Sentul, but was quickly contained.
These photographs were taken on May 15 by the then Agong Sultan Ismail Nasiruddin Shah, who ventured into the streets with his camera after signing the emergency orders.
The clock on the Sultan Abdul Samad building on Jalan Raja, shows it is afternoon but the streets are deserted due to a curfew in Kuala Lumpur. / Source: Sultan Ismail Nasiruddin Shah.
Batu Road, now Jalan Tuanku Abdul Rahman, during curfew on May 15. It was one of the main sites of carnage on May 13. / Source: Sultan Ismail Nasiruddin Shah
Jalan Bukit Bintang - a bustling street for shopping and entertainment to this day - was deserted on May 15, 1969 after Kuala Lumpur was placed on lockdown / Source: Sultan Ismail Nasiruddin Shah
The top left corner of the photograph indicates that this was near Hotel Odeon in Pudu. Not a soul was in sight during curfew on May 15, 1969. / Source: Sultan Ismail Nasiruddin Ismail.
On June 24, Parliament was suspended and the National Operations Council was established with Abdul Razak Hussein in charge. Power had shifted from PM Tunku Abdul Rahman to Razak.
In 1971, Parliament reconvened, with Razak as prime minister. Some scholars argue this showed the riots were part of a coup d'etat.
Razak believed unity could only be achieved with fair distribution of wealth. The bumiputera (Malays and indigenous groups) were the majority but owned just 2.4 percent of equity.
This led to the National Economic Policy in 1971, using affirmative action to grow bumiputera ownership. The ethos of that policy remains to this day.
The riots not only changed policies but left prolonged trauma on many who witnessed, survived and lost loved ones in the riots.
Malaysia is not alone in dealing with historical trauma. South Africa held truth and reconciliation hearings to move towards forgiveness post-Apartheid, while Germany took the punitive route to seek justice against Nazi criminality.
Malaysia can learn from how other nations overcame trauma, experts say, but must find a way that suits the country's unique circumstances. Half a century on, Malaysia must find a way to heal and move forward.
Malaysiakini has collected the accounts of the May 13 tragedy.