A hand grenade attack in the eastern Belgian city of Liege on Tuesday killed 4 and injured 64.

A two-year-old child is reportedly fighting for life in hospital. Six of other victims are said to be gravely injured.

Initial new reports said that around 12:30 local time a man lobbed several grenades at a bus shelter in Place Saint-Lambert, a busy downtown square. Witnesses reported four explosions and gun fire.

Later reports indicated one of two or more assailants threw stun grenades into the Liege courthouse, while another was hurled at a bus shelter, RTL-TV1 said.

At the time it was believed shots were fired across the square by gunmen posted on the rooftop of a bakery shop, with further shots heard later from across town.

In the confusion surrounding the scene it was reported police gave chase to the assailants after sealing off the square and killing one, ultimately cornering their prey in the Liege cathedral.

Police later established the gunman killed at the scene had acted alone, however. Investigators are still attempting to establish the motive behind the attack.   

Place Saint-Lambert is a busy crossroads: every day 1800 buses serve the square, which leads to downtown shopping streets.