The violence came after thousands of people marched in the Mediterranean city calling for the overthrow of President Bashar Assad's regime.
The coordinated attacks by gunboats and ground troops were the latest wave of a brutal offensive against anti-government protests launched at the beginning of the month.
The assault showed Mr Assad has no intention of scaling back the campaign even though it has brought international outrage and new European and US sanctions.
"We are being targeted from the ground and the sea," a frightened resident of al-Ramel district of Latakia, the hardest hit neighbourhood, told the AP.
"The shooting is intense. We cannot go out. They are raiding and breaking into people's homes," he added.
As the Syrian gunboats blasted waterfront districts, ground troops backed by tanks and security forces stormed several neighbourhoods in al-Ramel, sending terrified women and children fleeing to safer areas. Read More