A tanker carrying 960 tons of sulfuric acid sank in the north German port of Hamburg after colliding with a container ship on Monday evening. Though the chemical carrier's tanks weren't ruptured, the accident caused some of the liquid to escape via the ventilation system, firefighters said. Nine port employees and two police officers were hospitalized for breathing difficulties after inhaling the gas, said fire department spokesman Peter Braun. Emergency services began work early on Tuesday to pump the remaining sulfuric acid out of the double-hulled vessel and to refloat the tanker, which sank at dockside. Officials said reports that the captain of the German-registered tanker had been drunk at the time of collision were being investigated. No significant damage was reported on the container ship, which left the harbor shortly after the accident.