Complex sentence: The Hanson on two occasions encountered such fishing boats full of people and mined, but stayed clear and fired it's 40mm's on the vessels causing them to explode and sink taking the boat's inhabitants down with them.
Split into simpler sentences: The Hanson on two occasions encountered such fishing boats full of people and mined. Hanson fired it's 40mm's on the vessels causing them to explode and sink taking the boat's inhabitants down with them.