(a) maliciously shoots at an aircraft, vessel or vehicle in the service of the customs;

(b) maliciously shoots at, maims or wounds an officer while in the execution of his duty; or

(c) commits with violence any of the offences referred to in subsection (4),

shall be guilty of an offence and liable to imprisonment for a term not exceeding twenty years.

(2) A person who -

(a) while committing an offence under this Act is armed with a firearm or other offensive weapon; or

(b) while being so armed, is found with goods liable to forfeiture under this Act,

shall be guilty of an offence and liable to imprisonment for a term not exceeding ten years.

(3) A person who -

(a) while committing an offence under this Act is disguised in any way; or

(b) while being so disguised, is found with goods liable to forfeiture under this Act,

shall be guilty of an offence and liable to imprisonment for a term not exceeding three years.

(4) A person who -

(a) staves, breaks, destroys or throws overboard from an aircraft, vessel or vehicle any goods for the purpose of preventing the seizure thereof; or

(b) rescues, staves, breaks, destroys or throws overboard from an aircraft, vessel or vehicle any goods for the purpose of preventing the securing of those goods after they have been seized; or

(c) rescues a person arrested for any offence under this Act; or

(d) in any way obstructs an officer in the execution of his duty,

shall be guilty of an offence.

(5) For the purposes of this section "violence" means any criminal force or harm to a person, or any criminal mischief to property, or any threat or offer of that force, harm or mischief, or the carrying or use of any dangerous or offensive weapon so that terror is likely to be caused to any person, or conduct as is likely to cause in any person a reasonable apprehension of criminal force, harm or mischief, to him or to his property.