Complex sentence: In the first half of 1983 street protests were frequent, on May 1, two persons were killed in Kraków and one in Wrocław, two days later, two additional demonstrators were killed in Warsaw.
Split into simpler sentences: In the first half of 1983 street protests were frequent; on May 1, two persons were killed in Kraków and one in Wrocław. Two days later, two additional demonstrators were killed in Warsaw.